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有一张正文表,字段有d_id(文档id),createdate(创建日期),createtime(创建时间),title(标题)等- CREATE TABLE `content` (
- `d_id` int(10) unsigned NOT NULL AUTO_INCREMENT,
- `createdate` date NOT NULL DEFAULT '0000-00-00',
- `createtime` time NOT NULL DEFAULT '00:00:00',
- `title` text,
- ……
- PRIMARY KEY (`d_id`),
- KEY `createdate` (`createdate`,`createtime`),
- ) ENGINE=MyISAM
复制代码 执行以下sql- select * from content where title like '出版%' and createdate = '2011-11-29' order by d_id desc limit 1 ;
复制代码 慢日志:
# Query_time: 17.311505 Lock_time: 0.000670 Rows_sent: 0 Rows_examined: 1972413
为什么Rows_examined是1972413这么大?符合createdate = '2011-11-29'条件的记录仅有3000多条阿?
是索引建的有问题么?
是不应该做createdate和createtime的联合索引么?
实在是不解。求高人指点! |
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