MySQL查询剖析工具show profile

1、开启 profiling 参数

set profiling=1;

2、执行SQL语句

select * from sys_user;

select * from sys_menu;

3、获取系统保存的所有Query 的 profile 概要信息

mysql> show profiles;
+----------+------------+------------------------+
| Query_ID | Duration   | Query                  |
+----------+------------+------------------------+
|        1 | 0.00022875 | select * from sys_user |
|        2 | 0.00037200 | select * from sys_menu |
+----------+------------+------------------------+
2 rows in set, 1 warning (0.00 sec)

4、获取指定profile详细信息

mysql> show profile all for query 2;
+----------------------+----------+----------+------------+-------------------+---------------------+--------------+---------------+---------------+-------------------+-------------------+-------------------+-------+-----------------------+----------------------+-------------+
| Status               | Duration | CPU_user | CPU_system | Context_voluntary | Context_involuntary | Block_ops_in | Block_ops_out | Messages_sent | Messages_received | Page_faults_major | Page_faults_minor | Swaps | Source_function       | Source_file          | Source_line |
+----------------------+----------+----------+------------+-------------------+---------------------+--------------+---------------+---------------+-------------------+-------------------+-------------------+-------+-----------------------+----------------------+-------------+
| starting             | 0.000064 | 0.000029 |   0.000030 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | NULL                  | NULL                 |        NULL |
| checking permissions | 0.000007 | 0.000003 |   0.000003 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | check_access          | sql_authorization.cc |         809 |
| Opening tables       | 0.000015 | 0.000007 |   0.000008 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | open_tables           | sql_base.cc          |        5815 |
| init                 | 0.000020 | 0.000010 |   0.000010 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | handle_query          | sql_select.cc        |         128 |
| System lock          | 0.000007 | 0.000003 |   0.000003 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | mysql_lock_tables     | lock.cc              |         330 |
| optimizing           | 0.000003 | 0.000002 |   0.000001 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | optimize              | sql_optimizer.cc     |         158 |
| statistics           | 0.000011 | 0.000005 |   0.000006 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | optimize              | sql_optimizer.cc     |         374 |
| preparing            | 0.000008 | 0.000005 |   0.000004 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | optimize              | sql_optimizer.cc     |         482 |
| executing            | 0.000003 | 0.000001 |   0.000001 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | exec                  | sql_executor.cc      |         126 |
| Sending data         | 0.000193 | 0.000184 |   0.000000 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | exec                  | sql_executor.cc      |         202 |
| end                  | 0.000003 | 0.000003 |   0.000000 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | handle_query          | sql_select.cc        |         206 |
| query end            | 0.000005 | 0.000006 |   0.000000 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | mysql_execute_command | sql_parse.cc         |        4956 |
| closing tables       | 0.000007 | 0.000006 |   0.000000 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | mysql_execute_command | sql_parse.cc         |        5009 |
| freeing items        | 0.000017 | 0.000017 |   0.000000 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | mysql_parse           | sql_parse.cc         |        5622 |
| cleaning up          | 0.000010 | 0.000010 |   0.000000 |                 0 |                   0 |            0 |             0 |             0 |                 0 |                 0 |                 0 |     0 | dispatch_command      | sql_parse.cc         |        1931 |
+----------------------+----------+----------+------------+-------------------+---------------------+--------------+---------------+---------------+-------------------+-------------------+-------------------+-------+-----------------------+----------------------+-------------+
15 rows in set, 1 warning (0.00 sec)

上图横向意义
Status	状态
Duration	持续时间
CPU_user	CPU用户
CPU_system	CPU系统
Context_voluntary	上下文主动切换
Context_involuntary	上下文被动切换
Block_ops_in	阻塞的输入操作
Block_ops_out	阻塞的输出操作
Messages_sent	消息发送
Messages_received	消息接收
Page_faults_major	主分页错误
Page_faults_minor	次分页错误
Swaps	交换次数
Source_function	源功能
Source_file	源文件
Source_line	源代码行

上图纵向意义
starting	开始
checking permissions	权限检查
Opening tables	打开表
init	初始化
System lock	系统锁
optimizing	优化
statistics	统计
preparing	准备
executing	执行
Sending data	发送数据
Sorting result	排序
end	结束
query end	查询结束
closing tables	关闭表/去除TMP表
freeing items	释放物品
cleaning up	清理

一般情况下 ，使用以下语句就够了

show profile cpu,block io for query 2;