查询mysql的QPS

方法一 基于 questions  计算qps,基于  com_commit  com_rollback 计算tps

questions = show global status like 'questions';

uptime = show global status like 'uptime';

qps=questions/uptime

com_commit = show global status like 'com_commit';

com_rollback = show global status like 'com_rollback';

uptime = show global status like 'uptime';

tps=(com_commit + com_rollback)/uptime

方法二  基于 com_* 的status 变量计算tps ,qps

使用如下命令：

show global status where variable_name in('com_select','com_insert','com_delete','com_update');

获取间隔1s 的 com_*的值，并作差值运算

del_diff = (int(mystat2['com_delete'])   - int(mystat1['com_delete']) ) / diff

ins_diff = (int(mystat2['com_insert'])    - int(mystat1['com_insert']) ) / diff

sel_diff = (int(mystat2['com_select'])    - int(mystat1['com_select']) ) / diff

upd_diff = (int(mystat2['com_update'])   - int(mystat1['com_update']) ) / diff

总结：

Questions 是记录了从mysqld启动以来所有的select，dml 次数包括show 命令的查询的次数。这样多少有失准确性，比如很多数据库有监控系统在运行，每5秒对数据库进行一次show 查询来获取当前数据库的状态，而这些查询就被记录到QPS,TPS统计中，造成一定的"数据污染".

如果数据库中存在比较多的myisam表，则计算还是questions 比较合适。

如果数据库中存在比较多的innodb表，则计算以com_*数据来源比较合适