MySQL（发音：[ˌmaɪ ɛs kjuː ˈɛl]，但也经常读作My- SEQuel）是一个开放源码的关系数据库管理系统，开发者为瑞典MySQL AB公司，现为Sun公司的一部分。2009年Oracle宣布收购Sun公司，因此MySQL可能成为Oracle旗下产品。MySQL由于性能高、成 本低、可靠性好，已经成为最流行的开源数据库，被广泛地应用在Internet上的中小型网站中。随着MySQL的不断成熟，它也逐渐用于更多大规模网站 和应用，比如维基百科、Google和Facebook。非常流行的开源软件组合LAMP中的M就是指 MySQL。
下载:MySQL 5.5.4 m4mysql 在昨天发布了5.5 的第三个里程碑版后，今天又发布了第四个里程碑版。
主要是InnoDB方面的更新,目前只有for Linux on x86_64版本下载
Changes in MySQL 5.5.4:
InnoDB Plugin Notes:
* This release includes InnoDB Plugin 1.1.
Bugs fixed:
* The mysqld option to turn on support for large pages
was erroneously linked to the internal variable that
stores whether large file support is available. Turning
large_pages on would show both support for large pages
and for large files as available without actually turning
on support for large pages. Turning large_pages off would
show both as turned off without any actual implication to
large file support, which is compiled in at build time.
This bug was introduced in MySQL Server 5.5.3-m3.
(Bug#52716: http://bugs.mysql.com/bug.php?id=52716)