I have a concern regarding how an index is being used for a query. I've included the query (minus the fields) and the EXPLAIN output below. I'm curious why MySQL would indicate that it's using filesort for table 'd' since it's type is 'const.' The documentation indicates this means that only one row matched (which is true) and that it will use the fields from that table as constants through the rest of the query. Is this normal? The query is fast, but I want to make absolutely certain that it is perfectly optimized. select ...somefields... from thread a, user b, user c, forum d where d.forum_id=1 and a.forum_id=d.forum_id and a.forum_id = 1 and a.owner_id = b.user_id and a.reply_id = c.user_id order by modified desc limit 140,140 Here's the output of EXPLAIN: +-------+--------+-----------------+-------------+---------+------------+--- ---+----------------+ | table | type | possible_keys | key | key_len | ref | rows | Extra | +-------+--------+-----------------+-------------+---------+------------+--- ---+----------------+ | d | const | PRIMARY | PRIMARY | 4 | const | 1 | Using filesort | | a | range | forumupdate | forumupdate | 4 | NULL | 849 | where used | | b | eq_ref | PRIMARY,user_id | PRIMARY | 4 | a.owner_id | 1 | where used | | c | eq_ref | PRIMARY,user_id | PRIMARY | 4 | a.reply_id | 1 | where used | +-------+--------+-----------------+-------------+---------+------------+--- ---+----------------+ --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
