= Database Backend =

Initially, Trac only supported SQLite for its database backend (see PySqlite).

Postgresql support has been added as of Trac [milestone:0.9].

Mysql support will be added for Trac [milestone:0.10]
(see this [http://thread.gmane.org/gmane.comp.version-control.subversion.trac.devel/342/focus=348 status report]).

More generally, since milestone:0.10, Trac offers an easily extensible layer for
Database support (see [source:trunk/trac/db/api.py trac.db.api]).

The existing backends have been refactored and integrated in this
layer. There's currently bundled support for:
 * [http://www.sqlite.org SQLite], using PySqlite
 * [http://www.postgresql.org PostgreSQL], using a variety of bindings
   (''[http://initd.org/projects/psycopg1 psycopg1] (but see below)'', 
   [http://initd.org/projects/psycopg2 psycopg2], or 
   [http://pypgsql.sourceforge.net/ pyPgSQL]) (see #126 for historical notes)

There's some work in progress for the following:
 * MySQL (see #986)
 * Oracle (see #1874)

== Backend Specific Installation Instructions ==

=== SQLite === 

Should be installed out-of-the-box, provided you have installed the PySqlite bindings.

Known issues: see [query:keywords=~sqlite&status=!closed pysqlite-related tickets]


=== Postgresql ===

 * Have a working copy of Postgresql
 * Get the proper database driver for Python (see above)
 * Install [http://www.egenix.com/files/python/eGenix-mx-Extensions.html#Download-mxBASE mxBase], which is required for Postgresql support.
 * Create a database for your Trac environment
{{{
% createdb dbname
}}}
 * Run trac-admin to create a new Trac environment.  When prompted for a Database connection string, use:
{{{
postgres://user:pass@localhost:5432/dbname
}}}

See also #2441, which discusses the process of migration from SQLite to Postgresql.

For a postgresql recipe tested on CentOS4 (Red Hat -EL4) see [wiki:PostgresqlRecipe].

Note: Since Trac [milestone:0.10 0.10] the psycopg1 postgresql driver is no longer supported due to lack of unicode support.

Known issues: see [query:keywords=~postgres&status=!closed postgres-related tickets]


=== MySQL ===

MySQL is only experimentally supported with the patch attached to ticket #986.  
It also has several limitations.
 * Have a working copy of MySQL version 4.1.12 or greater.
 * [http://sourceforge.net/projects/mysql-python MySQLdb] - Python database driver for MySQL
 * Create a database and user for your Trac environment
{{{
% mysqladmin create dbname
% mysql
> grant all privileges on dbname.* to dbuser identified by 'dbpass';
> quit
}}}
 * Run trac-admin to create a new Trac environment.  When prompted for a database connection string, use:
{{{
mysql://dbuser:dbpass@host:port/dbname
}}}
 * or
{{{
mysql://dbuser:dbpass@host/dbname
}}}

Known issues: see [query:keywords=~mysql&status=!closed mysql-related tickets]

== Alternative Ideas for Database Independence ==

=== Object-Relational Mapper ===

An ORM could be used to provide a unified object interface to different RDBMS:
 * some people have been talking about using [http://sqlobject.org SQLObject] 
   to accomplish this goal of database independence.
 * [http://modeling.sourceforge.net/ Modeling]
   Another, more advanced (and more complex) OR-Mapper.
 * [http://www.sqlalchemy.org/ SQLAlchemy] seems to be also quite advanced 

Comparisions between both and more info on Python ORMs:
 * http://toulouse.amber.org/archives/2003/04/21/evaluating_objectrelational_migration.html
 * http://google.com/search?q=SQLObject+modeling

=== Store Tickets and Wiki pages directly in the Subversion repository ===

A compelling idea with many advantages. A page advocating this plan is TighterSubversionIntegration. There has also been a discussion on the Trac mailing list. All arguments from this discussion are summarized on the page [wiki:WhySQLite WhySQLite].

=== Other Alternatives ===

 * http://wiki.w4py.org/databaseintegration.html
 * http://adodb.sourceforge.net - the fast ADODB db abstraction layer (version available for python)