= MySQL and the MySQLdb Python bindings for MySQL =

 ''work in progress, only the most critical information is there for now''

Starting with [milestone:0.10] Trac can use MySQL for its DatabaseBackend, but only starting with [milestone:0.10.4] will MySQL be fully supported (at least that's the plan). So stick to [milestone:0.10.3] for now.


== Requirements ==
=== MySQL ===

In order to avoid several issues with unicode and international characters throughout Trac, we '''''strongly''''' advise MySQL users to only use databases having the ''`utf8`'' character set and the ''`utf8_general_ci`'' collation type. However, prior to [milestone:0.10.4] some of Trac indexes in ''utf8'' are incompatible with MySQL 4.1.x (too big), so anything before MySQL 5.0.x just will not work in this configuration.

Such databases can be created with the MySQL monitor, like that:
{{{
CREATE DATABASE trac DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci; 
}}}

To check what are the settings for your database, issue command:
{{{
mysql> USE TRAC;
Database changed
mysql> SHOW VARIABLES LIKE '%character%';
+--------------------------+--------------------
| Variable_name            | Value
+--------------------------+--------------------
| character_set_client     | cp1251
| character_set_connection | cp1251
| character_set_database   | utf8
| character_set_filesystem | binary
| character_set_results    | cp1251
| character_set_server     | utf8
| character_set_system     | utf8
| character_sets_dir       | C:\DevServer\Instal
+--------------------------+--------------------
8 rows in set (0.00 sec)
mysql>
}}}

See also #3884.

It has also been [comment:ticket:3659:5 recommended] to use InnoDB instead of MyISAM tables, though it's not completely clear at this point if this really helps. [http://dev.mysql.com/doc/refman/5.0/en/innodb-overview.html InnoDB] provides referential integrity
and transactions, so this should help.

=== MySQLdb ===
The recommended version is MySQL-python 1.2.2.

See http://cheeseshop.python.org/pypi/MySQL-python/1.2.2, which contains links to the .tar.gz source distribution as well as pre-built Windows eggs.

Older versions can be found at the [https://sourceforge.net/projects/mysql-python/ mysql-python] sourceforge project:
 - MySQL-python 1.2.1_p2 was the previously recommended version
 - MySQL-python 1.2.0-3.2.2, MySQL-python 1.2.2b2) were reported to have issues (see #3645).  
 - MySQL-python-1.2.2b2 was [googlegroups:trac-users:e291b3ecb4a990a1 reported] to solve an `AttributeError: 'array.array' object has no attribute 'startswith'` error seen when viewing a changeset... These problems ought to be fixed in 1.2.2b3; if they are not, or if you have other issues, please file a bug in the [https://sourceforge.net/tracker/?group_id=22307&atid=374932 MySQL-python Bug Tracker].

== Known Issues ==
=== Still Opened ===
[[TicketQuery(keywords=~mysql&status=!closed&group=milestone)]]

=== Typical Problems ===
[[TicketQuery(keywords=~mysql&resolution=worksforme&group=milestone)]]

(corresponding [query:keywords=~mysql&status=!closed&group=milestone custom query])

== Conversion ==

While a more robust method may be created for [milestone:0.10.4] to allow easy conversion from SQLite to MySQL, users have reported success with the [wiki:SqLiteToMySql following method].