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=================================
PostgreSQL specific model indexes
=================================
.. module:: django.contrib.postgres.indexes
The following are PostgreSQL specific :doc:`indexes </ref/models/indexes>`
available from the ``django.contrib.postgres.indexes`` module.
``BloomIndex``
==============
.. class:: BloomIndex(*expressions, length=None, columns=(), **options)
Creates a bloom_ index.
To use this index access you need to activate the bloom_ extension on
PostgreSQL. You can install it using the
:class:`~django.contrib.postgres.operations.BloomExtension` migration
operation.
Provide an integer number of bits from 1 to 4096 to the ``length``
parameter to specify the length of each index entry. PostgreSQL's default
is 80.
The ``columns`` argument takes a tuple or list of up to 32 values that are
integer number of bits from 1 to 4095.
.. _bloom: https://www.postgresql.org/docs/current/bloom.html
``BrinIndex``
=============
.. class:: BrinIndex(*expressions, autosummarize=None, pages_per_range=None, **options)
Creates a `BRIN index
<https://www.postgresql.org/docs/current/brin-intro.html>`_.
Set the ``autosummarize`` parameter to ``True`` to enable `automatic
summarization`_ to be performed by autovacuum.
The ``pages_per_range`` argument takes a positive integer.
.. _automatic summarization: https://www.postgresql.org/docs/current/brin-intro.html#BRIN-OPERATION
``BTreeIndex``
==============
.. class:: BTreeIndex(*expressions, fillfactor=None, **options)
Creates a B-Tree index.
Provide an integer value from 10 to 100 to the fillfactor_ parameter to
tune how packed the index pages will be. PostgreSQL's default is 90.
.. _fillfactor: https://www.postgresql.org/docs/current/sql-createindex.html#SQL-CREATEINDEX-STORAGE-PARAMETERS
``GinIndex``
============
.. class:: GinIndex(*expressions, fastupdate=None, gin_pending_list_limit=None, **options)
Creates a `gin index <https://www.postgresql.org/docs/current/gin.html>`_.
To use this index on data types not in the `built-in operator classes
<https://www.postgresql.org/docs/current/gin-builtin-opclasses.html>`_,
you need to activate the `btree_gin extension
<https://www.postgresql.org/docs/current/btree-gin.html>`_ on
PostgreSQL. You can install it using the
:class:`~django.contrib.postgres.operations.BtreeGinExtension` migration
operation.
Set the ``fastupdate`` parameter to ``False`` to disable the `GIN Fast
Update Technique`_ that's enabled by default in PostgreSQL.
Provide an integer number of kilobytes to the gin_pending_list_limit_
parameter to tune the maximum size of the GIN pending list which is used
when ``fastupdate`` is enabled.
.. _GIN Fast Update Technique: https://www.postgresql.org/docs/current/gin-implementation.html#GIN-FAST-UPDATE
.. _gin_pending_list_limit: https://www.postgresql.org/docs/current/runtime-config-client.html#GUC-GIN-PENDING-LIST-LIMIT
``GistIndex``
=============
.. class:: GistIndex(*expressions, buffering=None, fillfactor=None, **options)
Creates a `GiST index
<https://www.postgresql.org/docs/current/gist.html>`_. These indexes are
automatically created on spatial fields with :attr:`spatial_index=True
<django.contrib.gis.db.models.BaseSpatialField.spatial_index>`. They're
also useful on other types, such as
:class:`~django.contrib.postgres.fields.HStoreField` or the :ref:`range
fields <range-fields>`.
To use this index on data types not in the built-in `gist operator classes
<https://www.postgresql.org/docs/current/gist-builtin-opclasses.html>`_,
you need to activate the `btree_gist extension
<https://www.postgresql.org/docs/current/btree-gist.html>`_ on PostgreSQL.
You can install it using the
:class:`~django.contrib.postgres.operations.BtreeGistExtension` migration
operation.
Set the ``buffering`` parameter to ``True`` or ``False`` to manually enable
or disable `buffering build`_ of the index.
Provide an integer value from 10 to 100 to the fillfactor_ parameter to
tune how packed the index pages will be. PostgreSQL's default is 90.
.. _buffering build: https://www.postgresql.org/docs/current/gist-implementation.html#GIST-BUFFERING-BUILD
.. _fillfactor: https://www.postgresql.org/docs/current/sql-createindex.html#SQL-CREATEINDEX-STORAGE-PARAMETERS
``HashIndex``
=============
.. class:: HashIndex(*expressions, fillfactor=None, **options)
Creates a hash index.
Provide an integer value from 10 to 100 to the fillfactor_ parameter to
tune how packed the index pages will be. PostgreSQL's default is 90.
.. _fillfactor: https://www.postgresql.org/docs/current/sql-createindex.html#SQL-CREATEINDEX-STORAGE-PARAMETERS
``SpGistIndex``
===============
.. class:: SpGistIndex(*expressions, fillfactor=None, **options)
Creates an `SP-GiST index
<https://www.postgresql.org/docs/current/spgist.html>`_.
Provide an integer value from 10 to 100 to the fillfactor_ parameter to
tune how packed the index pages will be. PostgreSQL's default is 90.
.. _fillfactor: https://www.postgresql.org/docs/current/sql-createindex.html#SQL-CREATEINDEX-STORAGE-PARAMETERS
``OpClass()`` expressions
=========================
.. class:: OpClass(expression, name)
An ``OpClass()`` expression represents the ``expression`` with a custom
`operator class`_ that can be used to define functional indexes, functional
unique constraints, or exclusion constraints. To use it, you need to add
``'django.contrib.postgres'`` in your :setting:`INSTALLED_APPS`. Set the
``name`` parameter to the name of the `operator class`_.
For example::
Index(
OpClass(Lower("username"), name="varchar_pattern_ops"),
name="lower_username_idx",
)
creates an index on ``Lower('username')`` using ``varchar_pattern_ops``.
::
UniqueConstraint(
OpClass(Upper("description"), name="text_pattern_ops"),
name="upper_description_unique",
)
creates a unique constraint on ``Upper('description')`` using
``text_pattern_ops``.
::
ExclusionConstraint(
name="exclude_overlapping_ops",
expressions=[
(OpClass("circle", name="circle_ops"), RangeOperators.OVERLAPS),
],
)
creates an exclusion constraint on ``circle`` using ``circle_ops``.
.. _operator class: https://www.postgresql.org/docs/current/indexes-opclass.html
|
