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186 lines
6.7 KiB
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186 lines
6.7 KiB
Plaintext
=================================
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PostgreSQL specific model indexes
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=================================
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.. module:: django.contrib.postgres.indexes
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The following are PostgreSQL specific :doc:`indexes </ref/models/indexes>`
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available from the ``django.contrib.postgres.indexes`` module.
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``BloomIndex``
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==============
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.. class:: BloomIndex(*expressions, length=None, columns=(), **options)
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Creates a bloom_ index.
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To use this index access you need to activate the bloom_ extension on
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PostgreSQL. You can install it using the
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:class:`~django.contrib.postgres.operations.BloomExtension` migration
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operation.
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Provide an integer number of bits from 1 to 4096 to the ``length``
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parameter to specify the length of each index entry. PostgreSQL's default
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is 80.
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The ``columns`` argument takes a tuple or list of up to 32 values that are
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integer number of bits from 1 to 4095.
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.. _bloom: https://www.postgresql.org/docs/current/bloom.html
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``BrinIndex``
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=============
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.. class:: BrinIndex(*expressions, autosummarize=None, pages_per_range=None, **options)
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Creates a `BRIN index
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<https://www.postgresql.org/docs/current/brin-intro.html>`_.
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Set the ``autosummarize`` parameter to ``True`` to enable `automatic
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summarization`_ to be performed by autovacuum.
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The ``pages_per_range`` argument takes a positive integer.
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.. _automatic summarization: https://www.postgresql.org/docs/current/brin-intro.html#BRIN-OPERATION
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``BTreeIndex``
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==============
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.. class:: BTreeIndex(*expressions, fillfactor=None, **options)
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Creates a B-Tree index.
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Provide an integer value from 10 to 100 to the fillfactor_ parameter to
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tune how packed the index pages will be. PostgreSQL's default is 90.
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.. _fillfactor: https://www.postgresql.org/docs/current/sql-createindex.html#SQL-CREATEINDEX-STORAGE-PARAMETERS
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``GinIndex``
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============
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.. class:: GinIndex(*expressions, fastupdate=None, gin_pending_list_limit=None, **options)
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Creates a `gin index <https://www.postgresql.org/docs/current/gin.html>`_.
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To use this index on data types not in the `built-in operator classes
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<https://www.postgresql.org/docs/current/gin-builtin-opclasses.html>`_,
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you need to activate the `btree_gin extension
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<https://www.postgresql.org/docs/current/btree-gin.html>`_ on
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PostgreSQL. You can install it using the
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:class:`~django.contrib.postgres.operations.BtreeGinExtension` migration
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operation.
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Set the ``fastupdate`` parameter to ``False`` to disable the `GIN Fast
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Update Technique`_ that's enabled by default in PostgreSQL.
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Provide an integer number of bytes to the gin_pending_list_limit_ parameter
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to tune the maximum size of the GIN pending list which is used when
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``fastupdate`` is enabled.
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.. _GIN Fast Update Technique: https://www.postgresql.org/docs/current/gin-implementation.html#GIN-FAST-UPDATE
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.. _gin_pending_list_limit: https://www.postgresql.org/docs/current/runtime-config-client.html#GUC-GIN-PENDING-LIST-LIMIT
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``GistIndex``
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=============
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.. class:: GistIndex(*expressions, buffering=None, fillfactor=None, **options)
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Creates a `GiST index
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<https://www.postgresql.org/docs/current/gist.html>`_. These indexes are
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automatically created on spatial fields with :attr:`spatial_index=True
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<django.contrib.gis.db.models.BaseSpatialField.spatial_index>`. They're
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also useful on other types, such as
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:class:`~django.contrib.postgres.fields.HStoreField` or the :ref:`range
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fields <range-fields>`.
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To use this index on data types not in the built-in `gist operator classes
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<https://www.postgresql.org/docs/current/gist-builtin-opclasses.html>`_,
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you need to activate the `btree_gist extension
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<https://www.postgresql.org/docs/current/btree-gist.html>`_ on PostgreSQL.
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You can install it using the
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:class:`~django.contrib.postgres.operations.BtreeGistExtension` migration
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operation.
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Set the ``buffering`` parameter to ``True`` or ``False`` to manually enable
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or disable `buffering build`_ of the index.
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Provide an integer value from 10 to 100 to the fillfactor_ parameter to
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tune how packed the index pages will be. PostgreSQL's default is 90.
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.. _buffering build: https://www.postgresql.org/docs/current/gist-implementation.html#GIST-BUFFERING-BUILD
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.. _fillfactor: https://www.postgresql.org/docs/current/sql-createindex.html#SQL-CREATEINDEX-STORAGE-PARAMETERS
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``HashIndex``
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=============
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.. class:: HashIndex(*expressions, fillfactor=None, **options)
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Creates a hash index.
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Provide an integer value from 10 to 100 to the fillfactor_ parameter to
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tune how packed the index pages will be. PostgreSQL's default is 90.
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.. _fillfactor: https://www.postgresql.org/docs/current/sql-createindex.html#SQL-CREATEINDEX-STORAGE-PARAMETERS
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``SpGistIndex``
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===============
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.. class:: SpGistIndex(*expressions, fillfactor=None, **options)
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Creates an `SP-GiST index
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<https://www.postgresql.org/docs/current/spgist.html>`_.
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Provide an integer value from 10 to 100 to the fillfactor_ parameter to
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tune how packed the index pages will be. PostgreSQL's default is 90.
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.. versionchanged:: 4.1
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Support for covering SP-GiST indexes on PostgreSQL 14+ was added.
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.. _fillfactor: https://www.postgresql.org/docs/current/sql-createindex.html#SQL-CREATEINDEX-STORAGE-PARAMETERS
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``OpClass()`` expressions
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=========================
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.. class:: OpClass(expression, name)
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An ``OpClass()`` expression represents the ``expression`` with a custom
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`operator class`_ that can be used to define functional indexes, functional
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unique constraints, or exclusion constraints. To use it, you need to add
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``'django.contrib.postgres'`` in your :setting:`INSTALLED_APPS`. Set the
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``name`` parameter to the name of the `operator class`_.
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For example::
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Index(
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OpClass(Lower('username'), name='varchar_pattern_ops'),
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name='lower_username_idx',
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)
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creates an index on ``Lower('username')`` using ``varchar_pattern_ops``.
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::
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UniqueConstraint(
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OpClass(Upper('description'), name='text_pattern_ops'),
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name='upper_description_unique',
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)
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creates a unique constraint on ``Upper('description')`` using
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``text_pattern_ops``.
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::
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ExclusionConstraint(
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name='exclude_overlapping_ops',
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expressions=[
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(OpClass('circle', name='circle_ops'), RangeOperators.OVERLAPS),
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],
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)
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creates an exclusion constraint on ``circle`` using ``circle_ops``.
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.. versionchanged:: 4.1
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Support for exclusion constraints was added.
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.. _operator class: https://www.postgresql.org/docs/current/indexes-opclass.html
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