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 optionsclass Index(fields=[], name=None) [source]
Creates an index (B-Tree) in the database.
fieldsIndex.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.
nameIndex.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 (_).
See also
For a list of PostgreSQL-specific indexes, see django.contrib.postgres.indexes.
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https://docs.djangoproject.com/en/1.11/ref/models/indexes/