django1/docs/topics/db/tablespaces.txt

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===========
Tablespaces
===========
A common paradigm for optimizing performance in database systems is the use of
`tablespaces`_ to organize disk layout.
.. _`tablespaces`: http://en.wikipedia.org/wiki/Tablespace
.. warning::
Django does not create the tablespaces for you. Please refer to your
database engine's documentation for details on creating and managing
tablespaces.
Declaring tablespaces for tables
--------------------------------
A tablespace can be specified for the table generated by a model by supplying
the :attr:`~django.db.models.Options.db_tablespace` option inside the model's
``class Meta``. This option also affects tables automatically created for
:class:`~django.db.models.ManyToManyField`\ s in the model.
You can use the :setting:`DEFAULT_TABLESPACE` setting to specify a default value
for :attr:`~django.db.models.Options.db_tablespace`. This is useful for setting
a tablespace for the built-in Django apps and other applications whose code you
cannot control.
Declaring tablespaces for indexes
---------------------------------
You can pass the :attr:`~django.db.models.Field.db_tablespace` option to a
``Field`` constructor to specify an alternate tablespace for the ``Field``'s
column index. If no index would be created for the column, the option is
ignored.
You can use the :setting:`DEFAULT_INDEX_TABLESPACE` setting to specify
a default value for :attr:`~django.db.models.Field.db_tablespace`.
If :attr:`~django.db.models.Field.db_tablespace` isn't specified and you didn't
set :setting:`DEFAULT_INDEX_TABLESPACE`, the index is created in the same
tablespace as the tables.
An example
----------
.. code-block:: python
class TablespaceExample(models.Model):
name = models.CharField(max_length=30, db_index=True, db_tablespace="indexes")
data = models.CharField(max_length=255, db_index=True)
edges = models.ManyToManyField(to="self", db_tablespace="indexes")
class Meta:
db_tablespace = "tables"
In this example, the tables generated by the ``TablespaceExample`` model (i.e.
the model table and the many-to-many table) would be stored in the ``tables``
tablespace. The index for the name field and the indexes on the many-to-many
table would be stored in the ``indexes`` tablespace. The ``data`` field would
also generate an index, but no tablespace for it is specified, so it would be
stored in the model tablespace ``tables`` by default.
Database support
----------------
PostgreSQL and Oracle support tablespaces. SQLite and MySQL don't.
When you use a backend that lacks support for tablespaces, Django ignores all
tablespace-related options.