mysql> explain SELECT post_title,group_concat(cat_name) FROM wp_posts p LEFT JOIN wp_post2cat pc ON (p.ID=pc.post_id) JOIN wp_categories c ON (pc.category_id=c.cat_id) WHERE 1=1 AND (post_type = 'post' AND (post_status = 'publish')) GROUP BY post_date DESC,ID DESC LIMIT 0, 10; +----+-------------+-------+--------+---------------+---------+---------+--------------------------+------+--------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+--------+---------------+---------+---------+--------------------------+------+--------------------------+ | 1 | SIMPLE | p | ref | PRIMARY,blah2 | blah2 | 103 | const,const | 1 | Using where | | 1 | SIMPLE | pc | ref | post_id | post_id | 8 | wordpress.p.ID | 2 | Using where; Using index | | 1 | SIMPLE | c | eq_ref | PRIMARY | PRIMARY | 8 | wordpress.pc.category_id | 1 | | +----+-------------+-------+--------+---------------+---------+---------+--------------------------+------+--------------------------+ 3 rows in set (0.00 sec)