mysql> explain select film_id, count(*) from sakila.film group by film_id order by count(*); +----+-------------+-------+-------+---------------+---------+---------+------+------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+-------+---------------+---------+---------+------+------+----------------------------------------------+ | 1 | SIMPLE | film | index | NULL | PRIMARY | 2 | NULL | 951 | Using index; Using temporary; Using filesort | +----+-------------+-------+-------+---------------+---------+---------+------+------+----------------------------------------------+ 1 row in set (0.00 sec) mysql> notee