Single Field Indexes
Overview
Single field indexes are indexes with a reference to a single field of a document in a collection. These indexes improve single field query and sort performance. They also support TTL Indexes that automatically remove documents from a collection after a certain amount of time or at a specified clock time.
When creating a single-field index, you must specify the following details:
The field on which to create the index
The sort order for the indexed values as either ascending or descending
Note
The default _id_ index is an example of a single-field index.
This index is automatically created on the _id field when a new
collection is created.
Sample Data
The examples in this guide use the movies collection in the
sample_mflix database from the Atlas sample datasets. To learn how to create a free MongoDB Atlas cluster and
load the sample datasets, see the Get Started with Atlas guide.
Create Single-Field Index
Use the MongoDB\Collection::createIndex() method to create a single
field index. The following example creates an index in ascending order on the
title field:
$indexName = $collection->createIndex(['title' => 1]);
The following is an example of a query that is covered by the index created in the preceding code example:
$document = $collection->findOne(['title' => 'Sweethearts']); echo json_encode($document), PHP_EOL;
Additional Information
To view runnable examples that demonstrate how to manage indexes, see Optimize Queries by Using Indexes.
To learn more about single-field indexes, see Single Field Indexes in the MongoDB Server manual.
API Documentation
To learn more about any of the methods discussed in this guide, see the following API documentation: