# Τεκμηρίωση του Django - 5.2.8

# PostgreSQL specific model indexes

The following are PostgreSQL specific 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 `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.

## `BrinIndex`

class BrinIndex(*expressions, autosummarize=None, pages_per_range=None, **options)

  Creates a BRIN index.

  Set the `autosummarize` parameter to `True` to enable automatic summarization to be performed by autovacuum.

  The `pages_per_range` argument takes a positive integer.

## `BTreeIndex`

class BTreeIndex(*expressions, fillfactor=None, deduplicate_items=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.

  Provide a boolean value to the deduplicate_items parameter to control whether deduplication is enabled. PostgreSQL enables deduplication by default.

## `GinIndex`

class GinIndex(*expressions, fastupdate=None, gin_pending_list_limit=None, **options)

  Creates a gin index.

  To use this index on data types not in the built-in operator classes, you need to activate the btree_gin extension on PostgreSQL. You can install it using the `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.

## `GistIndex`

class GistIndex(*expressions, buffering=None, fillfactor=None, **options)

  Creates a GiST index. These indexes are automatically created on spatial fields with `spatial_index=True`. They’re also useful on other types, such as `HStoreField` or the range fields.

  To use this index on data types not in the built-in gist operator classes, you need to activate the btree_gist extension on PostgreSQL. You can install it using the `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.

## `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.

## `SpGistIndex`

class SpGistIndex(*expressions, fillfactor=None, **options)

  Creates an SP-GiST 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.

## `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 `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`.