1
===============================
2
Notes about supported databases
3
===============================
5
Django attempts to support as many features as possible on all database
6
backends. However, not all database backends are alike, and we've had to make
7
design decisions on which features to support and which assumptions we can make
10
This file describes some of the features that might be relevant to Django
11
usage. Of course, it is not intended as a replacement for server-specific
12
documentation or reference manuals.
17
Django expects the database to support transactions, referential integrity,
18
and Unicode support (UTF-8 encoding). Fortunately, MySQL_ has all these
19
features as available as far back as 3.23. While it may be possible to use
20
3.23 or 4.0, you'll probably have less trouble if you use 4.1 or 5.0.
25
`MySQL 4.1`_ has greatly improved support for character sets. It is possible to
26
set different default character sets on the database, table, and column.
27
Previous versions have only a server-wide character set setting. It's also the
28
first version where the character set can be changed on the fly. 4.1 also has
29
support for views, but Django currently doesn't use views.
34
`MySQL 5.0`_ adds the ``information_schema`` database, which contains detailed
35
data on all database schema. Django's ``inspectdb`` feature uses this
36
``information_schema`` if it's available. 5.0 also has support for stored
37
procedures, but Django currently doesn't use stored procedures.
39
.. _MySQL: http://www.mysql.com/
40
.. _MySQL 4.1: http://dev.mysql.com/doc/refman/4.1/en/index.html
41
.. _MySQL 5.0: http://dev.mysql.com/doc/refman/5.0/en/index.html
46
MySQL has several `storage engines`_ (previously called table types). You can
47
change the default storage engine in the server configuration.
49
The default engine is MyISAM_. The main drawback of MyISAM is that it doesn't
50
currently support transactions or foreign keys. On the plus side, it's
51
currently the only engine that supports full-text indexing and searching.
53
The InnoDB_ engine is fully transactional and supports foreign key references.
55
The BDB_ engine, like InnoDB, is also fully transactional and supports foreign
56
key references. However, its use seems to be deprecated.
58
`Other storage engines`_, including SolidDB_ and Falcon_, are on the horizon.
59
For now, InnoDB is probably your best choice.
61
.. _storage engines: http://dev.mysql.com/doc/refman/5.0/en/storage-engines.html
62
.. _MyISAM: http://dev.mysql.com/doc/refman/5.0/en/myisam-storage-engine.html
63
.. _BDB: http://dev.mysql.com/doc/refman/5.0/en/bdb-storage-engine.html
64
.. _InnoDB: http://dev.mysql.com/doc/refman/5.0/en/innodb.html
65
.. _Other storage engines: http://dev.mysql.com/doc/refman/5.1/en/storage-engines-other.html
66
.. _SolidDB: http://forge.mysql.com/projects/view.php?id=139
67
.. _Falcon: http://dev.mysql.com/doc/falcon/en/index.html
72
`MySQLdb`_ is the Python interface to MySQL. 1.2.1 is the first version that
73
has support for MySQL 4.1 and newer. If you are trying to use an older version
74
of MySQL, then 1.2.0 *might* work for you.
76
.. _MySQLdb: http://sourceforge.net/projects/mysql-python
78
Creating your database
79
----------------------
81
You can `create your database`_ using the command-line tools and this SQL::
83
CREATE DATABASE <dbname> CHARACTER SET utf8;
85
This ensures all tables and columns will use UTF-8 by default.
87
.. _create your database: http://dev.mysql.com/doc/refman/5.0/en/create-database.html
89
Connecting to the database
90
--------------------------
92
Refer to the `settings documentation`_.
94
Connection settings are used in this order:
96
1. ``DATABASE_OPTIONS``
97
2. ``DATABASE_NAME``, ``DATABASE_USER``, ``DATABASE_PASSWORD``, ``DATABASE_HOST``,
99
3. MySQL option files.
101
In other words, if you set the name of the database in ``DATABASE_OPTIONS``,
102
this will take precedence over ``DATABASE_NAME``, which would override
103
anything in a `MySQL option file`_.
105
Here's a sample configuration which uses a MySQL option file::
108
DATABASE_ENGINE = "mysql"
110
'read_default_file': '/path/to/my.cnf',
115
database = DATABASE_NAME
117
passwd = DATABASE_PASSWORD
118
default-character-set = utf8
120
Several other MySQLdb connection options may be useful, such as ``ssl``,
121
``use_unicode``, ``init_command``, and ``sql_mode``. Consult the
122
`MySQLdb documentation`_ for more details.
124
.. _settings documentation: http://www.djangoproject.com/documentation/settings/#database-engine
125
.. _MySQL option file: http://dev.mysql.com/doc/refman/5.0/en/option-files.html
126
.. _MySQLdb documentation: http://mysql-python.sourceforge.net/
131
When Django generates the schema, it doesn't specify a storage engine, so
132
tables will be created with whatever default storage engine your database
133
server is configured for. The easiest solution is to set your database server's
134
default storage engine to the desired engine.
136
If you're using a hosting service and can't change your server's default
137
storage engine, you have a couple of options.
139
* After the tables are created, execute an ``ALTER TABLE`` statement to
140
convert a table to a new storage engine (such as InnoDB)::
142
ALTER TABLE <tablename> ENGINE=INNODB;
144
This can be tedious if you have a lot of tables.
146
* Another option is to use the ``init_command`` option for MySQLdb prior to
147
creating your tables::
151
"init_command": "SET storage_engine=INNODB",
155
This sets the default storage engine upon connecting to the database.
156
After your tables have been created, you should remove this option.
158
* Another method for changing the storage engine is described in
161
.. _AlterModelOnSyncDB: http://code.djangoproject.com/wiki/AlterModelOnSyncDB