{"title":"Model index reference","version":"2.0","locale":"zh-hans","docname":"ref/models/indexes","url":"/zh-hans/2.0/ref/models/indexes/","canonical":"https://djangodocs.dev/zh-hans/2.0/ref/models/indexes/","summary":"New in Django 1.11 Index classes ease creating database indexes. They can be added using the Meta.indexes option. This document explains the API references of Index…","html":"

Model index referenceLink to this heading#

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Index classes ease creating database indexes. They can be added using the\nMeta.indexes option. This document\nexplains the API references of Index which includes the index\noptions.

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Index optionsLink to this heading#

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\nclass Index(fields=[], name=None, db_tablespace=None)Link to this definition#
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Creates an index (B-Tree) in the database.

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fieldsLink to this heading#

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\nIndex.fieldsLink to this definition#
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A list of the name of the fields on which the index is desired.

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By default, indexes are created with an ascending order for each column. To\ndefine an index with a descending order for a column, add a hyphen before the\nfield's name.

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For example Index(fields=['headline', '-pub_date']) would create SQL with\n(headline, pub_date DESC). Index ordering isn't supported on MySQL. In that\ncase, a descending index is created as a normal index.

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nameLink to this heading#

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\nIndex.nameLink to this definition#
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The name of the index. If name isn't provided Django will auto-generate a\nname. For compatibility with different databases, index names cannot be longer\nthan 30 characters and shouldn't start with a number (0-9) or underscore (_).

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db_tablespaceLink to this heading#

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\nIndex.db_tablespaceLink to this definition#
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The name of the database tablespace to use for\nthis index. For single field indexes, if db_tablespace isn't provided, the\nindex is created in the db_tablespace of the field.

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If Field.db_tablespace isn't specified (or if the index uses multiple\nfields), the index is created in tablespace specified in the\ndb_tablespace option inside the model's\nclass Meta. If neither of those tablespaces are set, the index is created\nin the same tablespace as the table.

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