From fa0fbd011812e9df52c9e5684d4cf953c6f75d8e Mon Sep 17 00:00:00 2001 From: Brion Vibber Date: Tue, 22 Dec 2009 20:18:27 -0800 Subject: [PATCH] Fix for massively slow friends timeline query due to indexing bug introduced with repeats. Sorting on notice.id when our primary selector was notice_inbox.user_id caused a filesort and table scan of the notice table. Switchng to notice_inbox's notice_id means we can use our index, and everything comes right up. Before: mysql> explain SELECT notice.id AS id FROM notice JOIN notice_inbox ON notice.id = notice_inbox.notice_id WHERE notice_inbox.user_id = 18574 AND notice.repeat_of IS NULL ORDER BY notice.id DESC LIMIT 61 OFFSET 0; +----+-------------+--------------+--------+------------------------------------+---------+---------+-------------------------------+--------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------------+--------+------------------------------------+---------+---------+-------------------------------+--------+----------------------------------------------+ | 1 | SIMPLE | notice_inbox | ref | PRIMARY,notice_inbox_notice_id_idx | PRIMARY | 4 | const | 102600 | Using index; Using temporary; Using filesort | | 1 | SIMPLE | notice | eq_ref | PRIMARY | PRIMARY | 4 | stoica.notice_inbox.notice_id | 1 | Using index | +----+-------------+--------------+--------+------------------------------------+---------+---------+-------------------------------+--------+----------------------------------------------+ After: mysql> explain SELECT notice.id AS id FROM notice JOIN notice_inbox ON notice.id = notice_inbox.notice_id WHERE notice_inbox.user_id = 18574 AND notice.repeat_of IS NULL ORDER BY notice_id DESC LIMIT 61 OFFSET 0; +----+-------------+--------------+--------+------------------------------------+---------+---------+-------------------------------+--------+--------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------------+--------+------------------------------------+---------+---------+-------------------------------+--------+--------------------------+ | 1 | SIMPLE | notice_inbox | ref | PRIMARY,notice_inbox_notice_id_idx | PRIMARY | 4 | const | 102816 | Using where; Using index | | 1 | SIMPLE | notice | eq_ref | PRIMARY,notice_repeatof_idx | PRIMARY | 4 | stoica.notice_inbox.notice_id | 1 | Using where | +----+-------------+--------------+--------+------------------------------------+---------+---------+-------------------------------+--------+--------------------------+ --- classes/User.php | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/classes/User.php b/classes/User.php index ae709b46b6..484dc8c82b 100644 --- a/classes/User.php +++ b/classes/User.php @@ -543,7 +543,7 @@ class User extends Memcached_DataObject // NOTE: we sort by fave time, not by notice time! - $qry .= 'ORDER BY notice.id DESC '; + $qry .= 'ORDER BY notice_id DESC '; if (!is_null($offset)) { $qry .= "LIMIT $limit OFFSET $offset";