我有这个查询,我执行它需要很长时间
SELECT DISTINCT ticket.`id`,
`sender`,
`text`,
`receivedtime`,
`priorityid`,
`cityid`,
`categoryid`,
`statusid`,
`activeuserid`,
`note`,
`operationid`,
'' AS SMSHistory,
'' AS replySMS,
'' AS ticketHistory
FROM `ticket`
LEFT OUTER JOIN tickethistory
ON tickethistory.ticketid = ticket.id
LEFT OUTER JOIN users
ON tickethistory.uid = users.uid
ORDER BY ticket.`id` DESC
LIMIT 0, 50
这是表结构:
CREATE TABLE `ticket` (
`id` int(10) NOT NULL AUTO_INCREMENT,
`sender` varchar(50) NOT NULL,
`text` text NOT NULL,
`receivedTime` datetime NOT NULL,
`priorityId` int(10) NOT NULL,
`cityId` int(10) NOT NULL,
`categoryId` int(10) NOT NULL,
`statusId` int(10) NOT NULL,
`activeUserId` int(11) NOT NULL,
`note` text NOT NULL,
`operationId` int(10) NOT NULL,
`gateway` varchar(80) NOT NULL,
KEY `Index 1` (`id`),
KEY `sender` (`sender`),
KEY `priorityId` (`priorityId`),
KEY `cityId` (`cityId`),
KEY `categoryId` (`categoryId`),
KEY `statusId` (`statusId`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
----
CREATE TABLE `tickethistory` (
`id` int(10) NOT NULL AUTO_INCREMENT,
`ticketId` int(10) NOT NULL,
`uid` int(11) NOT NULL,
`actionId` int(10) NOT NULL,
`time` datetime NOT NULL,
`param1` text NOT NULL,
`param2` text NOT NULL,
`param3` text NOT NULL,
KEY `Index 1` (`id`),
KEY `ticketId` (`ticketId`),
KEY `uid` (`uid`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
----
用户:
CREATE TABLE IF NOT EXISTS `users` (
`Uid` int(11) NOT NULL AUTO_INCREMENT,
`UserName` varchar(255) NOT NULL,
`Upassword` varchar(32) NOT NULL,
`UName` text NOT NULL,
`Ucountry` text NOT NULL,
`Umobile` varchar(255) NOT NULL,
`UregisterDate` date NOT NULL DEFAULT '0000-00-00',
`Ugroup` char(1) NOT NULL DEFAULT 'U',
`Usender` varchar(11) NOT NULL DEFAULT 'SMS',
`Ucredits` decimal(11,2) NOT NULL DEFAULT '0.00',
`Uemail` varchar(255) NOT NULL,
`CreditUpdatedDate` date DEFAULT NULL,
`USMSC` varchar(30) NOT NULL,
`repeatedDuration` int(10) DEFAULT '0',
`langid` varchar(10) DEFAULT 'Ar',
`parentId` int(11) NOT NULL DEFAULT '0',
`Usess` varchar(255) NOT NULL DEFAULT '0',
PRIMARY KEY (`Uid`),
UNIQUE KEY `UserName` (`UserName`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
这是解释命令结果:
'id';'select_type';'table';'type';'possible_keys';'key';'key_len';'ref';'rows';'Extra'
'1';'SIMPLE';'ticket';'ALL';'';'';'';'';'348580';'Using temporary; Using filesort'
'1';'SIMPLE';'tickethistory';'ref';'ticketId';'ticketId';'4';'ticket.id';'2';'Distinct'
'1';'SIMPLE';'users';'eq_ref';'PRIMARY';'PRIMARY';'4';'tickethistory.uid';'1';'Using index; Distinct'
答案 0 :(得分:1)
EXPLAIN表明它正在使用临时表和filesort对TICKET表中的记录进行排序。这有点奇怪,因为你正在排序的ID上有一个索引,但鉴于它匹配350K记录,这可能就是为什么它很慢。
当您尝试查找最新记录时,请尝试包含限制“where”子句,例如将搜索限制为上周(不要忘记在receivedTime上创建索引)。
您可能还考虑没有从ticketHistory到User的外部联接 - UID列是非NULL,因此没有匹配用户的记录应该没有。