评论：实例说明optimize table在优化mysql时很重要 http://blog.51yip.com/mysql/1222.html －－一步，二步，三步，N步，二行脚印 Tue, 07 Jun 2022 01:26:20 +0000 http://wordpress.org/?v=2.9.1 hourly 1 来自：涛涛 http://blog.51yip.com/mysql/1222.html/comment-page-1#comment-17848 涛涛 Wed, 20 Feb 2019 10:02:46 +0000 http://blog.51yip.com/?p=1222#comment-17848 OPTIMIZE 一张删除了几千万条数据的表大概要多长时间 OPTIMIZE 一张删除了几千万条数据的表大概要多长时间

]]> 来自：fanyank http://blog.51yip.com/mysql/1222.html/comment-page-1#comment-17806 fanyank Sun, 21 Oct 2018 13:14:41 +0000 http://blog.51yip.com/?p=1222#comment-17806 楼上正解，引用MySQL官方文档给出的解释 In the InnoDB multi-versioning scheme, a row is not physically removed from the database immediately when you delete it with an SQL statement. InnoDB only physically removes the corresponding row and its index records when it discards the update undo log record written for the deletion. This removal operation is called a purge, and it is quite fast, usually taking the same order of time as the SQL statement that did the deletion. 楼上正解，引用MySQL官方文档给出的解释
In the InnoDB multi-versioning scheme, a row is not physically removed from the database immediately when you delete it with an SQL statement. InnoDB only physically removes the corresponding row and its index records when it discards the update undo log record written for the deletion. This removal operation is called a purge, and it is quite fast, usually taking the same order of time as the SQL statement that did the deletion.

]]> 来自：蓝天 http://blog.51yip.com/mysql/1222.html/comment-page-1#comment-17683 蓝天 Thu, 02 Nov 2017 15:23:11 +0000 http://blog.51yip.com/?p=1222#comment-17683 这应该是类似于oracle的高水位吧 这应该是类似于oracle的高水位吧

]]> 来自：有点不同的见地 http://blog.51yip.com/mysql/1222.html/comment-page-1#comment-17602 有点不同的见地 Wed, 03 May 2017 09:32:05 +0000 http://blog.51yip.com/?p=1222#comment-17602 对于为什么删除了表数据表的空间并没有减少的问题我有点不同的看法； 我觉得是因为mysql MVCC的控制原因，删除了的数据其实还在那里，标记了删除的版本号 并不是你所说的空在那里。 对于为什么删除了表数据表的空间并没有减少的问题我有点不同的看法；
我觉得是因为mysql MVCC的控制原因，删除了的数据其实还在那里，标记了删除的版本号 并不是你所说的空在那里。

]]> 来自：royce http://blog.51yip.com/mysql/1222.html/comment-page-1#comment-3451 royce Fri, 19 Apr 2013 05:57:09 +0000 http://blog.51yip.com/?p=1222#comment-3451 不错，建议支持新浪微博分享 不错，建议支持新浪微博分享

]]> 来自：ruochen http://blog.51yip.com/mysql/1222.html/comment-page-1#comment-410 ruochen Thu, 10 Mar 2011 11:26:11 +0000 http://blog.51yip.com/?p=1222#comment-410 注意这个bug * InnoDB Storage Engine: The OPTIMIZE TABLE statement would reset the auto-increment counter for an InnoDB table. Now the auto-increment value is preserved across this operation. (Bug#18274: http://bugs.mysql.com/bug.php?id=18274) 注意这个bug

* InnoDB Storage Engine: The OPTIMIZE TABLE statement would
reset the auto-increment counter for an InnoDB table. Now the
auto-increment value is preserved across this operation.
(Bug#18274: http://bugs.mysql.com/bug.php?id=18274)

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