Hi, all. I think I'm misunderstanding something basic about indexes. I have a SELECT like so:
SELECT * FROM a LEFT JOIN b ON a.a_id = b.a_id JOIN c ON a.c_id = c.c_id JOIN d ON c.d_id = d.d_id JOIN e ON c.e_id = e.e_id WHERE a.timestamp BETWEEN 20040101000000 AND 20040101235959 GROUP BY c.d_id, c.e_id All of the id fields are primary indexes. I've already created an index on a.timestamp, and that works all right. I tried creating an index on a for the SELECT: KEY `reporting` (`a_id`,`c_id`,`timestamp`) and an index on c for the GROUP BY: KEY `reporting` (`c_id`,`d_id`,`e_id`) But EXPLAIN shows that MySQL isn't even considering the key on a, and chooses the primary key on c over my index. Clearly I'm confused about how indexes are used in a JOIN/WHERE situation: can anyone enlighten me? ____________________________________________________________ Eamon Daly -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
