Still waters run deep

摘要： WarningBefore using innodb_force_recovery ensure that you have a backup copy of your database in case you need to start over. You should always begin by setting innodb_force_recovery to a lower value. Incrementally increase the setting as required. Only use an innodb_force_recovery setting of 3 or g 阅读全文

摘要： Baronwrotenice article comparing locking hints in MySQL and SQL Server.In MySQL/Innodb LOCK IN SHARE MODE and SELECT FOR UPDATE are more than hints. Behavior will be different from normal SELECT statements. Here is simple example: 1 SESSION1: 2 mysql> begin; 3 Query OK, 0 rows affected (0.00 sec) 阅读全文

摘要： MyISAM storage engine has key compression which makes its indexes much smaller, allowing better fit in caches and so improving performance dramatically. Actually packed indexes not a bit longer rows is frequent reason of MyISAM performing better than Innodb. In this article I’ll get in a bit more de 阅读全文

摘要： 好多人在调优Mysql的时候，总是对open_tables和opend_tables两个参数分别不清。网上好多解释都是这样的：open_tables:当前打开表的数量opened_tables:当前已经打开表的数量很简单的解释，可是这两句话看起来有点类似。下面我来解释一下：open_tables:是当前在缓存中打开表的数量。opened_tables:是mysql自启动起，打开表的数量。我们知道，假如没有缓存的话，那么mysql服务在每次执行一个语句的时候，都会先打开一个表。当sql语句执行完成后，则把这个表关掉。这就是opend_tables中的值。而open_tables这个值，是mysq 阅读全文

摘要： One command, which few people realize exists isSHOW OPEN TABLES– it allows you to examine what tables do you have open right now:1 mysql> show open tables from test;2 +----------+-------+--------+-------------+3 | Database | Table | In_use | Name_locked |4 +----------+-------+--------+----------- 阅读全文