我有一个基于3列的复合索引,其中两个约束在我的查询中,第三个约束在子句中,但mysql不使用索引进行排序。优化我的mysql查询以使用索引进行排序
explain select * from videos where public_private='public' and approved='yes' order by number_of_views desc; +----+-------------+--------+------+--------------------------------+------+---------+------+---------+-----------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------+------+--------------------------------+------+---------+------+---------+-----------------------------+ | 1 | SIMPLE | videos | ALL | approved,approved_3,approved_2 | NULL | NULL | NULL | 1476818 | Using where; Using filesort | +----+-------------+--------+------+--------------------------------+------+---------+------+---------+-----------------------------+
表结构如下:
CREATE TABLE `videos` (
`indexer` int(9) NOT NULL auto_increment,
`user_id` int(9) default NULL,
`public_private` varchar(24) default NULL,
`approved` varchar(24) default NULL,
`number_of_views` int(9) default NULL,
PRIMARY KEY (`indexer`),
KEY `approved` (`approved`,`user_id`),
KEY `approved_3` (`approved`,`public_private`,`indexer`),
KEY `approved_2` (`approved`,`public_private`,`number_of_views`),
) ENGINE=MyISAM AUTO_INCREMENT=1969091 DEFAULT CHARSET=utf8 |
我应该怎么做来强制MySQL使用索引排序的结果?
FORCE INDEX解决了问题。现在查询执行速度快得多,而且您对查询匹配大部分数据库是正确的。 – 2009-07-18 11:02:47
好东西,很高兴它的工作。 – zombat 2009-07-18 16:36:20