Tablespaces

A common paradigm for optimizing performance in database systems is the use of tablespaces to organize disk layout.

警告

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 db_tablespace option inside the model's class Meta. This option also affects tables automatically created for ManyToManyFields in the model.

You can use the DEFAULT_TABLESPACE setting to specify a default value for 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 db_tablespace option to an Index constructor to specify the name of a tablespace to use for the index. For single field indexes, you can pass the db_tablespace option to a Field constructor to specify an alternate tablespace for the field's column index. If the column doesn't have an index, the option is ignored.

You can use the DEFAULT_INDEX_TABLESPACE setting to specify a default value for db_tablespace.

If db_tablespace isn't specified and you didn't set DEFAULT_INDEX_TABLESPACE, the index is created in the same tablespace as the tables.

一个例子

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)
    shortcut = models.CharField(max_length=7)
    edges = models.ManyToManyField(to="self", db_tablespace="indexes")

    class Meta:
        db_tablespace = "tables"
        indexes = [models.Index(fields=['shortcut'], db_tablespace='other_indexes')]

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. The index for the shortcut field would be stored in the other_indexes tablespace.

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.

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