Still waters run deep

摘要： 今天在写一个Perl脚本，想自动化查找出MySQL数据库中可能无效的索引，于是根据朝阳的书上提到的一些规则，我来设计了一些判断方法，其中发现某个我想要的值就是SHOW INDEX FROM table里的Cardinality，于是查了下它的含义以验证我的想法。MySQL中SHOW INDEX FROM table 会有以下结果列| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comme 阅读全文

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