Database Manual / Indexes / Create

Specify an Index Name

When you create an index, you can give the index a custom name. Giving your index a name helps distinguish different indexes on your collection. For example, you can more easily identify the indexes used by a query in the query plan's explain results if your indexes have distinct names.

To specify the index name, include the name option when you create the index:

db.<collection>.createIndex(
   { <field>: <value> },
   { name: "<indexName>" }
)

About this Task

Before you specify an index name, consider the following:

  • Index names must be unique. Creating an index with the name of an existing index returns an error.

  • You can't rename an existing index. Instead, you must drop and recreate the index with a new name.

Default Index Names

If you don't specify a name during index creation, the system generates the name by concatenating each index key field and value with underscores. For example:

IndexDefault Name

{ score : 1 }

score_1

{ content : "text", "description.tags": "text" }

content_text_description.tags_text

{ category : 1, locale : "2dsphere"}

category_1_locale_2dsphere

{ "fieldA" : 1, "fieldB" : "hashed", "fieldC" : -1 }

fieldA_1_fieldB_hashed_fieldC_-1

Procedure

A blog collection contains data about blog posts and user interactions.

Create a text index on the content, users.comments, and users.profiles fields. Set the index name to InteractionsTextIndex:

db.blog.createIndex(
   {
     content: "text",
     "users.comments": "text",
     "users.profiles": "text"
   },
   {
     name: "InteractionsTextIndex"
   }
)

Results

After you create the index, you can use the db.collection.getIndexes() method to get the index name:

db.blog.getIndexes()

Output:

[
  { v: 2, key: { _id: 1 }, name: '_id_' },
  {
    v: 2,
    key: { _fts: 'text', _ftsx: 1 },
    name: 'InteractionsTextIndex',
    weights: { content: 1, 'users.comments': 1, 'users.profiles': 1 },
    default_language: 'english',
    language_override: 'language',
    textIndexVersion: 3
  }
]

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