我遇到此查詢需要幾秒鐘才能完成的問題。我已經嘗試了很多優化,但是我現在在拍攝空白。在此查詢中使用RIGHT JOIN時JOIN速度很慢
表是以下(而不是絕對的完全正常化特別是軌道表)
CREATE TABLE `tracks` (
`id` int(14) unsigned NOT NULL AUTO_INCREMENT,
`artist` varchar(200) NOT NULL,
`track` varchar(200) NOT NULL,
`album` varchar(200) NOT NULL,
`path` text NOT NULL,
`tags` text NOT NULL,
`priority` int(10) NOT NULL DEFAULT '0',
`lastplayed` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`lastrequested` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`usable` int(1) NOT NULL DEFAULT '0',
`accepter` varchar(200) NOT NULL DEFAULT '',
`lasteditor` varchar(200) NOT NULL DEFAULT '',
`hash` varchar(40) DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `hash` (`hash`),
FULLTEXT KEY `searchindex` (`tags`,`artist`,`track`,`album`),
FULLTEXT KEY `artist` (`artist`,`track`,`album`,`tags`)
) ENGINE=MyISAM AUTO_INCREMENT=3336 DEFAULT CHARSET=utf8
CREATE TABLE `esong` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`hash` varchar(40) COLLATE utf8_bin NOT NULL,
`len` int(10) unsigned NOT NULL,
`meta` text COLLATE utf8_bin NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `hash` (`hash`)
) ENGINE=InnoDB AUTO_INCREMENT=16032 DEFAULT CHARSET=utf8 COLLATE=utf8_bin
CREATE TABLE `efave` (
`id` int(10) unsigned NOT NULL DEFAULT '0',
`inick` int(10) unsigned NOT NULL,
`isong` int(10) unsigned NOT NULL,
UNIQUE KEY `inick` (`inick`,`isong`),
KEY `isong` (`isong`),
CONSTRAINT `inick` FOREIGN KEY (`inick`) REFERENCES `enick` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `isong` FOREIGN KEY (`isong`) REFERENCES `esong` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8
CREATE TABLE `enick` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT
`nick` varchar(30) COLLATE utf8_bin NOT NULL,
`dta` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
`dtb` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
PRIMARY KEY (`id`),
KEY `nick` (`nick`)
) ENGINE=InnoDB AUTO_INCREMENT=488 DEFAULT CHARSET=utf8 COLLATE=utf8_bin
,我試圖用正常的速度執行查詢是以下
SELECT esong.meta, tracks.id FROM tracks RIGHT JOIN esong ON tracks.hash = esong.hash JOIN efave ON efave.isong = esong.id JOIN enick ON efave.inick = enick.id WHERE enick.nick = lower('nickname');
如果刪除RIGHT JOIN並將其更改爲JOIN,則速度很快
EXPLAIN向我提供此結果,似乎在efave中存在一個小問題但我不知道如何解決這個問題
+----+-------------+--------+--------+---------------+---------+---------+-----------------------+------+----------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+--------+--------+---------------+---------+---------+-----------------------+------+----------+--------------------------+
| 1 | SIMPLE | enick | ref | PRIMARY,nick | nick | 92 | const | 1 | 100.00 | Using where; Using index |
| 1 | SIMPLE | efave | ref | inick,isong | inick | 4 | radiosite.enick.id | 12 | 100.00 | Using index |
| 1 | SIMPLE | esong | eq_ref | PRIMARY | PRIMARY | 4 | radiosite.efave.isong | 1 | 100.00 | |
| 1 | SIMPLE | tracks | ALL | hash | NULL | NULL | NULL || 100.00 | |
+----+-------------+--------+--------+---------------+---------+---------+-----------------------+------+----------+--------------------------+
'tracks'表的'COLLATE'值是什麼? – 2012-04-05 00:30:06