Model index reference
Index classes ease creating database indexes. They can be added using the Meta.indexes
option. This document explains the API references of Index
which includes the index options.
Referencing built-in indexes
Indexes are defined in django.db.models.indexes
, but for convenience they’re imported into django.db.models
. The standard convention is to use from django.db import models
and refer to the indexes as models.<IndexClass>
.
Index
options
-
class Index(fields=[], name=None, db_tablespace=None)
[source] -
Creates an index (B-Tree) in the database.
fields
-
Index.fields
A list of the name of the fields on which the index is desired.
By default, indexes are created with an ascending order for each column. To define an index with a descending order for a column, add a hyphen before the field’s name.
For example Index(fields=['headline', '-pub_date'])
would create SQL with (headline, pub_date DESC)
. Index ordering isn’t supported on MySQL. In that case, a descending index is created as a normal index.
Support for column ordering on SQLite
Column ordering is supported on SQLite 3.3.0+ and only for some database file formats. Refer to the SQLite docs for specifics.
name
-
Index.name
The name of the index. If name
isn’t provided Django will auto-generate a name. For compatibility with different databases, index names cannot be longer than 30 characters and shouldn’t start with a number (0-9) or underscore (_).
db_tablespace
-
Index.db_tablespace
The name of the database tablespace to use for this index. For single field indexes, if db_tablespace
isn’t provided, the index is created in the db_tablespace
of the field.
If Field.db_tablespace
isn’t specified (or if the index uses multiple fields), the index is created in tablespace specified in the db_tablespace
option inside the model’s class Meta
. If neither of those tablespaces are set, the index is created in the same tablespace as the table.
See also
For a list of PostgreSQL-specific indexes, see django.contrib.postgres.indexes
.
© Django Software Foundation and individual contributors
Licensed under the BSD License.
https://docs.djangoproject.com/en/2.0/ref/models/indexes/