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

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;

{"_id":...,"plot":"A musical comedy duo...",
"genres":["Musical"],...,"title":"Sweethearts",...}

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.