php - can't getting the exact error in aggregation on mongodb -

php - can't getting the exact error in aggregation on mongodb -

when trying aggregation query on sample mongo database of 25 entries, works. when same method applied entire mongodb of 317000 entries, doesn't respond. it's not showing kind of error. such problems.

$mongo = new mongo("localhost"); $collection = $mongo->selectcollection("sampledb","analytics"); $cursor = $collection->aggregate( array( array( '$group' => array( '_id' => array( 'os'=>'$feat_os', 'minprice'=>'$finder_input_1', 'max_price'=>'$finder_input_2', 'feat_quadcode'=>'$feat_quadcore' ), 'count' => array('$sum' => 1) ) ), array('$out'=>"result") ) );

php mongodb aggregation-framework