+----+-------------+----------------------+--------+-------------------------+------------+---------+-----------------------------------+------+-----------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+----------------------+--------+-------------------------+------------+---------+-----------------------------------+------+-----------------------------------------------------------+ | 1 | SIMPLE | Groups_3 | ref | PRIMARY,Groups1,Groups2 | Groups1 | 67 | const | 79 | Using where; Using index; Using temporary; Using filesort | | 1 | SIMPLE | CachedGroupMembers_2 | ref | DisGrouMem | DisGrouMem | 5 | rt3.Groups_3.id | 2 | Using where; Using index | | 1 | SIMPLE | main | eq_ref | PRIMARY | PRIMARY | 4 | rt3.CachedGroupMembers_2.MemberId | 1 | | | 1 | SIMPLE | Principals_1 | eq_ref | PRIMARY | PRIMARY | 4 | rt3.main.id | 1 | Using where; Distinct | | 1 | SIMPLE | ACL_4 | range | ACL1 | ACL1 | 54 | NULL | 37 | Using where; Using index; Distinct | +----+-------------+----------------------+--------+-------------------------+------------+---------+-----------------------------------+------+-----------------------------------------------------------