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Cleaned up docs/databases.txt 

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=============================== ===============================
Notes About Supported Databases Notes about supported databases
=============================== ===============================
Django attempts to support as many features as possible on all databases. Django attempts to support as many features as possible on all database
However, since not all database servers are identical, there is obviously backends. However, not all database backends are alike, and we've had to make
going to be some variations. This file describes some of the design decisions on which features to support and which assumptions we can make
features that might relevant to Django usage. It is not intended as a safely.
replacement for server-specific documentation or reference manuals.
MySQL Notes This file describes some of the features that might be relevant to Django
usage. Of course, it is not intended as a replacement for server-specific
documentation or reference manuals.
MySQL notes
=========== ===========
Django expects the database to support transactions, referential integrity, Django expects the database to support transactions, referential integrity,
and Unicode support (UTF-8 encoding). Fortunately MySQL_ has all these and Unicode support (UTF-8 encoding). Fortunately, MySQL_ has all these
features as available as far back as 3.23. While it may be possible to use features as available as far back as 3.23. While it may be possible to use
3.23 or 4.0, you will probably have less trouble if you use 4.1 or 5.0. 3.23 or 4.0, you'll probably have less trouble if you use 4.1 or 5.0.
MySQL-4.1 MySQL 4.1
--------- ---------
MySQL-4.1_ has greatly improved support for character sets. It is possible to `MySQL 4.1`_ has greatly improved support for character sets. It is possible to
set different default character sets on the database, table, and column. set different default character sets on the database, table, and column.
Previous versions have only a server-wide character set setting. It's also the Previous versions have only a server-wide character set setting. It's also the
first version where the character set can be changed on the fly. 4.1 also has first version where the character set can be changed on the fly. 4.1 also has
support for views, but these are not currently used by Django. support for views, but Django currently doesn't use views.
MySQL-5.0 MySQL 5.0
--------- ---------
MySQL-5.0_ adds the ``information_schema`` database, which contains detailed `MySQL 5.0`_ adds the ``information_schema`` database, which contains detailed
data on all database schema. This is used for Django's ``inspectdb`` feature, data on all database schema. Django's ``inspectdb`` feature uses this
when it is available. 5.0 also has support for stored procedures, but these ``information_schema`` if it's available. 5.0 also has support for stored
are not currently used by Django. procedures, but Django currently doesn't use stored procedures.
.. _MySQL: http://www.mysql.com/ .. _MySQL: http://www.mysql.com/
.. _MySQL-4.1: http://dev.mysql.com/doc/refman/4.1/en/index.html .. _MySQL 4.1: http://dev.mysql.com/doc/refman/4.1/en/index.html
.. _MySQL-5.0: http://dev.mysql.com/doc/refman/5.0/en/index.html .. _MySQL 5.0: http://dev.mysql.com/doc/refman/5.0/en/index.html
Storage Engines Storage engines
--------------- ---------------
MySQL has several `storage engines`_ (previously called table types). You can MySQL has several `storage engines`_ (previously called table types). You can
change the default storage engine in the server configuration. change the default storage engine in the server configuration.
The default one is MyISAM_. The main drawback of MyISAM is that it does not The default engine is MyISAM_. The main drawback of MyISAM is that it doesn't
currently have support for transactions or foreign keys. On the plus side, it currently support transactions or foreign keys. On the plus side, it's
is currently the only engine that supports full-text indexing and searching. currently the only engine that supports full-text indexing and searching.
The InnoDB_ engine is fully transactional and supports foreign key references. The InnoDB_ engine is fully transactional and supports foreign key references.
The BDB_ engine, like InnoDB, is also fully transactional and supports foreign The BDB_ engine, like InnoDB, is also fully transactional and supports foreign
key references. However, it's use seems to be somewhat deprecated. key references. However, its use seems to be deprecated.
`Other storage engines`_, including SolidDB_ and Falcon_, are on the horizon. `Other storage engines`_, including SolidDB_ and Falcon_, are on the horizon.
For now, InnoDB is probably your best choice. For now, InnoDB is probably your best choice.
@ -66,25 +69,25 @@ For now, InnoDB is probably your best choice.
MySQLdb MySQLdb
------- -------
`MySQLdb`_ is the Python interface to MySQL. 1.2.1 is the first version which `MySQLdb`_ is the Python interface to MySQL. 1.2.1 is the first version that
has support for MySQL-4.1 and newer. If you are trying to use an older version has support for MySQL 4.1 and newer. If you are trying to use an older version
of MySQL, then 1.2.0 *may* work for you. of MySQL, then 1.2.0 *might* work for you.
.. _MySQLdb: http://sourceforge.net/projects/mysql-python .. _MySQLdb: http://sourceforge.net/projects/mysql-python
Creating your database Creating your database
~~~~~~~~~~~~~~~~~~~~~~ ----------------------
You can `create your database`_ using the command-line tools and this SQL:: You can `create your database`_ using the command-line tools and this SQL::
CREATE DATABASE <dbname> CHARACTER SET utf8; CREATE DATABASE <dbname> CHARACTER SET utf8;
This ensures all tables and columns will use utf8 by default. This ensures all tables and columns will use UTF-8 by default.
.. _create your database: http://dev.mysql.com/doc/refman/5.0/en/create-database.html .. _create your database: http://dev.mysql.com/doc/refman/5.0/en/create-database.html
Connecting to the database Connecting to the database
~~~~~~~~~~~~~~~~~~~~~~~~~~ --------------------------
Refer to the `settings documentation`_. Refer to the `settings documentation`_.
@ -114,8 +117,8 @@ Here's a sample configuration which uses a MySQL option file::
passwd = DATABASE_PASSWORD passwd = DATABASE_PASSWORD
default-character-set = utf8 default-character-set = utf8
There are several other MySQLdb connection options which may be useful, such Several other MySQLdb connection options may be useful, such as ``ssl``,
as ``ssl``, ``use_unicode``, ``init_command``, and ``sql_mode``; consult the ``use_unicode``, ``init_command``, and ``sql_mode``. Consult the
`MySQLdb documentation`_ for more details. `MySQLdb documentation`_ for more details.
.. _settings documentation: http://www.djangoproject.com/documentation/settings/#database-engine .. _settings documentation: http://www.djangoproject.com/documentation/settings/#database-engine
@ -123,39 +126,36 @@ as ``ssl``, ``use_unicode``, ``init_command``, and ``sql_mode``; consult the
.. _MySQLdb documentation: http://mysql-python.sourceforge.net/ .. _MySQLdb documentation: http://mysql-python.sourceforge.net/
Creating your tables Creating your tables
~~~~~~~~~~~~~~~~~~~~ --------------------
When Django generates the schema, it doesn't specify a storage engine, so they When Django generates the schema, it doesn't specify a storage engine, so
will be created with whatever default `storage engine`__ your database server tables will be created with whatever default storage engine your database
is configured for. The easiest solution is to set your database server's default server is configured for. The easiest solution is to set your database server's
storage engine to the desired engine. default storage engine to the desired engine.
__ `storage engines`_ If you're using a hosting service and can't change your server's default
If you are using a hosting service and can't change your server's default
storage engine, you have a couple of options. storage engine, you have a couple of options.
After the tables is created, all that is needed to convert it to a new storage * After the tables are created, execute an ``ALTER TABLE`` statement to
engine (such as InnoDB) is:: convert a table to a new storage engine (such as InnoDB)::
ALTER TABLE <tablename> ENGINE=INNODB; ALTER TABLE <tablename> ENGINE=INNODB;
With a lot of tables, this can be tedious. This can be tedious if you have a lot of tables.
Another option is to use the ``init_command`` option for MySQLdb prior to * Another option is to use the ``init_command`` option for MySQLdb prior to
creating your tables:: creating your tables::
DATABASE_OPTIONS = { DATABASE_OPTIONS = {
... # ...
"init_command": "SET storage_engine=INNODB", "init_command": "SET storage_engine=INNODB",
... # ...
} }
This sets the default storage engine upon connecting to the database. After This sets the default storage engine upon connecting to the database.
your tables are set up and running in production, you should remove this After your tables have been created, you should remove this option.
option.
Another method for changing the storage engine is described in * Another method for changing the storage engine is described in
AlterModelOnSyncDB_. AlterModelOnSyncDB_.
.. _AlterModelOnSyncDB: http://code.djangoproject.com/wiki/AlterModelOnSyncDB .. _AlterModelOnSyncDB: http://code.djangoproject.com/wiki/AlterModelOnSyncDB