mysql> explain SELECT DISTINCT -> r.id -> , r.user_id -> , r.text -> , r.date_added -> , r.date_modified -> -> , u.username AS user_nick -> , u.date_signup AS user_signup_date -> , i.gender AS user_gender -> , CONCAT_WS( ' ', i.firstname, i.surname ) AS user_name -> , i.title AS user_title -> , o.user_id IS NOT NULL AS user_is_online -> , IFNULL( p.has_avatar, 0 ) AS user_has_avatar -> , c.postCount -> FROM forum_reply AS r -> LEFT JOIN user AS u ON ( r.user_id = u.user_id ) -> LEFT JOIN forum_user_postcount AS c ON r.user_id = c.userId -> LEFT JOIN user_info AS i ON ( r.user_id = i.user_id ) -> LEFT JOIN user_session AS o ON ( r.user_id = o.user_id AND o.updated >= DATE_SUB( NOW(), INTERVAL 5 MINUTE ) ) -> LEFT JOIN user_photo AS p ON ( r.user_id = p.user_id ) -> WHERE r.topic_id = 23113 -> AND r.date_deleted IS NULL -> ORDER BY r.date_added DESC LIMIT 20; -> LIMIT 20; +----+-------------+-------+--------+-------------------------------------------+----------+---------+---------------------------+------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+--------+-------------------------------------------+----------+---------+---------------------------+------+----------------------------------------------+ | 1 | SIMPLE | r | ref | date_deleted,topic_id.date_added,topic_id | topic_id | 13 | const,const | 3170 | Using where; Using temporary; Using filesort | | 1 | SIMPLE | u | eq_ref | PRIMARY | PRIMARY | 3 | leidenonline_nu.r.user_id | 1 | | | 1 | SIMPLE | c | eq_ref | PRIMARY | PRIMARY | 3 | leidenonline_nu.r.user_id | 1 | | | 1 | SIMPLE | i | eq_ref | PRIMARY | PRIMARY | 3 | leidenonline_nu.r.user_id | 1 | | | 1 | SIMPLE | o | ref | user_id,updated | user_id | 3 | leidenonline_nu.r.user_id | 1 | | | 1 | SIMPLE | p | eq_ref | PRIMARY | PRIMARY | 3 | leidenonline_nu.r.user_id | 1 | | +----+-------------+-------+--------+-------------------------------------------+----------+---------+---------------------------+------+----------------------------------------------+ # User@Host: nucom_engine[nucom_engine] @ [192.168.2.7] # Query_time: 4 Lock_time: 0 Rows_sent: 20 Rows_examined: 36729