Mysql uses profile to analyze sql overhead code
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Mysql uses profile to analyze sql overhead
1.使用之前先查看当前数据库的版本信息,低版本无法使用. show version(); 或者 show variables like '%version%' 2.查看profiling show variables like '%profil%' ; result: +------------------------+-------+ | Variable_name | Value | +------------------------+-------+ | have_profiling | YES | --只读变量,用于控制是否由系统变量开启或禁用profiling | profiling | OFF | --开启SQL语句剖析功能 | profiling_history_size | 15 | --设置保留profiling的数目,缺省为15,范围为0至100,为0时将禁用p show profiles; 查看是否开启,效果同上. 3.查看使用说明 help profile; 4.开启profile set profiling=1; 赋值时候不要有多余的空格. 5.运行sql,查看对应的profile select * from test ; show profiles; result: +----------+------------+--------------------------------------------------------------------------------------------------------------------------+ | Query_ID | Duration | Query | +----------+------------+--------------------------------------------------------------------------------------------------------------------------+ | 28 | 0.00033575 | select * from test | +----------+------------+--------------------------------------------------------------------------------------------------------------------------+ 分析sql性能,分析的时候可以加上对应的开销字段 show profile [cpu,io][all] for query 28 ; show profile for query 28 ; +----------------------+----------+ | Status | Duration | +----------------------+----------+ | starting | 5.7E-5 | | checking permissions | 7E-6 | | Opening tables | 1.7E-5 | | init | 2.3E-5 | | System lock | 8E-6 | | optimizing | 5E-6 | | statistics | 1.1E-5 | | preparing | 9E-6 | | executing | 3E-6 | | Sending data | 8.8E-5 | | end | 5E-6 | | query end | 6E-6 | | closing tables | 5E-6 | | freeing items | 7.8E-5 | | cleaning up | 1.5E-5 | +----------------------+----------+ 6.关闭 set profiling=off;
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