PHP Manual: Creating An Index

Creating An Index

MongoDB supports indexes, and they are very easy to add on a collection. To create an index, you specify the field name and direction: ascending (1) or descending (-1). The following creates an ascending index on the "i" field:


<?php
$connection = new MongoClient();
$collection = $connection->database->collectionName;

$coll->ensureIndex( array( "i" => 1 ) );  // create index on "i"
$coll->ensureIndex( array( "i" => -1, "j" => 1 ) );  // index on "i" descending, "j" ascending
?>

Indexing is critical for good read performance as your data grows. If you are not familiar with indexing, check out the MongoCollection::ensureIndex documentation and the core » MongoDB indexing documentation.