More about indexes
Compound indexes:
$myCol->createIndex( [ _id => 1, ts => -1 ] )
Indexes can be made on nested fields:
$myCol->createIndex( [ "article.title" => -1 ] )
Indexes can be made on array values:
insert( [ '_id' => 42, 'values' => [ 'fourty', 'two' ] ] );
$myCol->createIndex( [ 'values' => 1 ] );]]>
Searching with regexp: %^%:
$myCol->find( [ 'name' => new MongoRegex( '/^tan/i' ) ] )