mysql中sum的优化和索引问题

//表结构CREATE TABLE IF NOT EXISTS `radacct` (  `RadAcctId` bigint(21) NOT NULL AUTO_INCREMENT,  `UserName` varchar(64) NOT NULL DEFAULT '',  `AcctSessionTime` int(12) DEFAULT NULL,  `AcctInputOctets` bigint(12) DEFAULT NULL,  `AcctOutputOctets` bigint(12) DEFAULT NULL,  ...  ......  PRIMARY KEY (`RadAcctId`),  KEY `UserName` (`UserName`),  KEY `AcctSessionTime` (`AcctSessionTime`),  KEY `AcctInputOctets` (`AcctInputOctets`),  KEY `AcctOutputOctets` (`AcctOutputOctets`)) ENGINE=MyISAM  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=456017; $sql = 'SELECT UserName, count(*) AS numOfSession, sum(AcctSessionTime) AS Time, sum(AcctInputOctets) AS Upload, sum(AcctOutputOctets) AS Download, sum(AcctInputOctets+AcctOutputOctets) AS Bandwidth FROM radacct GROUP BY UserName';  mysql> explain SELECT UserName, count(*) AS numOfSession, sum( AcctSessionTime ) AS Time, sum( AcctInputOctets ) AS Upload, sum( AcctOutputOctets ) AS Download, sum( AcctInputOctets + AcctOutputOctets ) AS Bandwidth FROM radacct GROUP BY UserName; +----+-------------+---------+------+---------------+------+---------+------+--------+---------------------------------+| id | select_type | table   | type | possible_keys | key  | key_len | ref  | rows   | Extra                           |+----+-------------+---------+------+---------------+------+---------+------+--------+---------------------------------+|  1 | SIMPLE      | radacct | ALL  | NULL          | NULL | NULL    | NULL | 456010 | Using temporary; Using filesort |+----+-------------+---------+------+---------------+------+---------+------+--------+---------------------------------+

回复讨论(解决方案)

首先，如果使用的计算，索引就已经失效了，所以你加不加索引没效果。

我的思路是这样的，如果表变得的不平凡，可以考虑缓存一份数据的办法来代替你每次的查询。

首先，如果使用的计算，索引就已经失效了，所以你加不加索引没效果。

我的思路是这样的，如果表变得的不平凡，可以考虑缓存一份数据的办法来代替你每次的查询。
好了 骚年 再没人来分都全给你了

加上分页什么的就更慢了我的思路是这样的，如果表变得的不平凡，可以考虑缓存一份数据的办法来代替你每次的查询。