demo->poiConcat->aggregate( [ [ '$match' => [ 'ts' => new MongoRegex( '/^cuisine=/' ) ] ], [ '$unwind' => '$ts' ], /* Match again to get rid of all the useless ts */ [ '$match' => [ 'ts' => new MongoRegex( '/^cuisine=/' ) ] ], ] ); var_dump( $res['result'] ); ?>]]>