MySQL Query Profiler 介绍

MySQL Query Profiler

查看MySQL语法详细执行时间与CPU/记忆体使用量: MySQL Query Profiler 
MySQL的SQL语法调整主要都是使用EXPLAIN,但是这个并没办法知道详细的Ram(Memory)/CPU等使用量. 
于MySQL 5.0.37以上开始支援MySQL Query Profiler,可以查询到此SQL会执行多少时间,并看出CPU/Memory使用量,执行过程中System lock, Table lock花多少时间等等. 
MySQL Query Profile详细介绍可见: Using the New MySQL Query Profiler (2007.04.05发表) 
效能分析主要分下述三种(转载自上篇): 
• Bottleneck analysis - focuses on answering the questions: What is my database server waiting on; what is a user connection waiting on; what is a piece of SQL code waiting on? 
• Workload analysis - examines the server and who is logged on to determine the resource usage and activity of each. 
• Ratio-based analysis - utilizes a number of rule-of-thumb ratios to gauge performance of a database, user connection, or piece of code. 
MySQL Query Profile使用方法
启动
• mysql> set profiling=1; #此命令于MySQL会于information_schema的database建立一个PROFILING的table来纪录. 
SQL profiles show 
• mysql> show profiles; #从启动之后所有语法及使用时间,含错误语法都会纪录. 
• ex: (root@localhost) [test]> show profiles; #注意Query_ID,下面执行时间统计等,都是依Query_ID在纪录
• +----------+------------+------------------------ ---+ 
• | Query_ID | Duration | Query | 
• +----------+------------+------------------------ ---+ 
• | 1 | 0.00090400 | show profile for query 1 | 
• | 2 | 0.00008700 | select * from users | 
• | 3 | 0.00183800 | show tables | 
• | 4 | 0.00027600 | mysql> show profiles | 
• +----------+------------+------------------------ ---+ 

查询所有花费时间加总
• mysql> select sum(duration) from information_schema.profiling where query_id=1; # Query ID = 1 
• +---------------+ 
• | sum(duration) | 
• +---------------+ 
• | 0.000447 | 
• +---------------+ 

查询各执行阶段花费多少时间
• mysql> show profile for query 1; # Query ID = 1 
• +--------------------+------------+ 
• | Status | Duration | 
• +--------------------+------------+ 
• | (initialization) | 0.00006300 | 
• | Opening tables | 0.00001400 | 
• | System lock | 0.00000600 | 
• | Table lock | 0.00001000 | 
• | init | 0.00002200 | 
• | optimizing | 0.00001100 | 
• | statistics | 0.00009300 | 
• | preparing | 0.00001700 | 
• | executing | 0.00000700 | 
• | Sending data | 0.00016800 | 
• | end | 0.00000700 | 
• | query end | 0.00000500 | 
• | freeing items | 0.00001200 | 
• | closing tables | 0.00000800 | 
• | logging slow query | 0.00000400 | 
• +--------------------+------------+ 

查询各执行阶段花费的各种资源列表
• mysql> show profile cpu for query 1; # Query ID = 1 
• +--------------------------------+----------+---- ------+------------+ 
• | Status | Duration | CPU_user | CPU_system | 
• +--------------------------------+----------+---- ------+------------+ 
• | (initialization) | 0.000007 | 0 | 0 | 
• | checking query cache for query | 0.000071 | 0 | 0 | 
• | Opening tables | 0.000024 | 0 | 0 | 
• | System lock | 0.000014 | 0 | 0 | 
• | Table lock | 0.000055 | 0.001 | 0 | 
• | init | 0.000036 | 0 | 0 | 
• | optimizing | 0.000013 | 0 | 0 | 
• | statistics | 0.000021 | 0 | 0 | 
• | preparing | 0.00002 | 0 | 0 | 
• | executing | 0.00001 | 0 | 0 | 
• | Sending data | 0.015072 | 0.011998 | 0 | 
• | end | 0.000021 | 0 | 0 | 
• | query end | 0.000011 | 0 | 0 | 
• | storing result in query cache | 0.00001 | 0 | 0 | 
• | freeing items | 0.000018 | 0 | 0 | 
• | closing tables | 0.000019 | 0 | 0 | 
• | logging slow query | 0.000009 | 0 | 0 | 
• +--------------------------------+----------+---- ------+------------+ 

• mysql> show profile IPC for query 1; 
• +--------------------------------+----------+---- -----------+-------------------+ 
• | Status | Duration | Messages_sent | Messages_received | 
• +--------------------------------+----------+---- -----------+-------------------+ 
• | (initialization) | 0.000007 | 0 | 0 | 
• | checking query cache for query | 0.000071 | 0 | 0 | 
• | Opening tables | 0.000024 | 0 | 0 | 
• | System lock | 0.000014 | 0 | 0 | 
• | Table lock | 0.000055 | 0 | 0 | 
• | init | 0.000036 | 0 | 0 | 
• | optimizing | 0.000013 | 0 | 0 | 
• | statistics | 0.000021 | 0 | 0 | 
• | preparing | 0.00002 | 0 | 0 | 
• | executing | 0.00001 | 0 | 0 | 
• | Sending data | 0.015072 | 0 | 0 | 
• | end | 0.000021 | 0 | 0 | 
• | query end | 0.000011 | 0 | 0 | 
• | storing result in query cache | 0.00001 | 0 | 0 | 
• | freeing items | 0.000018 | 0 | 0 | 
• | closing tables | 0.000019 | 0 | 0 | 
• | logging slow query | 0.000009 | 0 | 0 | 
• +--------------------------------+----------+---- -----------+-------------------+ 

其它属性列表
• ALL - displays all information 
• BLOCK IO - displays counts for block input and output operations 
• CONTEXT SWITCHES - displays counts for voluntary and involuntary context switches 
• IPC - displays counts for messages sent and received 
• MEMORY - is not currently implemented 
• PAGE FAULTS - displays counts for major and minor page faults 
• SOURCE - displays the names of functions from the source code, together with the name and line number of the file in which the function occurs 
• SWAPS - displays swap counts 
设定Profiling存的Size 
• mysql> show variables where variable_name='profiling_history_size'; #预设是15
关闭
• mysql> set profiling=0;