我在检查 MySQL 的慢查询日志时,发现了以下条目:
# Time: 131108 4:16:34
# Query_time: 14.726425 Lock_time: 0.000000 Rows_sent: 0 Rows_examined: 1
SET timestamp=1383884194;
UPDATE `Artist` SET ImageFilename = NULL, Title = 'Elton John', PopularityRating = 657, UniqueID = NULL, Description = NULL, IsFeatured = 0, FeaturedText = '', MetaDescription = '', MetaTitle = NULL, _Temporary_LastUpdOn = '2013-11-08 04:15:58 ', _Temporary_Flag = 0, _Deleted = 0, _DeletedOn = NULL, Priority = 0 WHERE ID = 3449748;
正如您所看到的,执行这个查询竟然花费了惊人的14.72秒,而它只是一个通过主键进行简单更新的WHERE
。我已经尝试重新执行该查询,现在执行时间为0.095秒,更加合理。
有任何想法可以调试为什么那个特定的时间会花费这么长时间吗?
编辑1:query_cache%变量
mysql> SHOW variables where variable_name like 'query_cache%';
+------------------------------+-----------+
| Variable_name | Value |
+------------------------------+-----------+
| query_cache_limit | 1048576 |
| query_cache_min_res_unit | 4096 |
| query_cache_size | 210763776 |
| query_cache_type | ON |
| query_cache_wlock_invalidate | OFF |
+------------------------------+-----------+
编辑2:艺术家表信息
CREATE TABLE `artist` (
`ID` bigint(20) NOT NULL,
`ImageFilename` mediumtext,
`Title` varchar(1000) DEFAULT NULL,
`PopularityRating` int(11) DEFAULT '0',
`UniqueID` mediumtext,
`Description` mediumtext,
`IsFeatured` tinyint(1) DEFAULT '0',
`FeaturedText` mediumtext,
`_Temporary_LastUpdOn` datetime DEFAULT '0001-01-01 00:00:00',
`_Temporary_Flag` tinyint(1) DEFAULT '0',
`_Deleted` tinyint(1) DEFAULT '0',
`_DeletedOn` datetime DEFAULT NULL,
`Priority` int(11) DEFAULT '0',
`MetaDescription` varchar(2000) DEFAULT NULL,
`MetaTitle` mediumtext,
PRIMARY KEY (`ID`),
KEY `_Temporary_Flag` (`_Temporary_Flag`),
KEY `_Deleted` (`_Deleted`),
KEY `Priority` (`Priority`),
KEY `PopularityRating` (`PopularityRating`),
KEY `Title` (`Title`(255)),
KEY `IsFeatured` (`IsFeatured`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8