PROFILE 可以跟踪查询语句各个阶段 Time，IO，CPU，MEMORY 等资源使用情况，比较详细。所以系统一般不会记录太多。启用是全局的，所以每个连接都保持语句的资源使用情况。
查看 PROFILE 是否启用：
- mysql> select @@profiling;
- +-------------+
- | @@profiling |
- +-------------+
- | 0 |
- +-------------+
- mysql> show variables like '%profiling%';
- +------------------------+-------+
- | variable_name | value |
- +------------------------+-------+
- | have_profiling | yes |
- | profiling | off |
- | profiling_history_size | 15 |
- +------------------------+-------+
have_profiling ：是否可使用 profiling
profiling ：是否启用
profiling_history_size ： 保留最近执行的记录数量。默认15，最大100，0相当于禁用。
启用(为全局变量)：
- mysql> set profiling = 1;
- mysql> set profiling_history_size = 10;
查看当前连接最近执行语句情况，编号越大为当前最近执行的。
- mysql> show profiles;
- +----------+------------+-----------------------------------------+
- | query_id | duration | query |
- +----------+------------+-----------------------------------------+
- | 2 | 0.00705950 | show variables like '%profiling%' |
- | 3 | 0.00127400 | select * from mysql.user |
- | 4 | 0.00029100 | select * from mysql.user |
- | 5 | 0.00040850 | select * from mysql.user limit 10 |
- | 6 | 5.00128000 | select sleep(5) |
- | 7 | 0.00044425 | select * from mysql.user limit 1 |
- | 8 | 0.00436100 | show variables like '%profiling%' |
- | 9 | 0.00047725 | select * from mysql.slow_log |
- | 10 | 0.00052150 | select * from mysql.slow_log order by 1 |
- | 11 | 0.00049775 | select * from mysql.slow_log order by 2 |
- +----------+------------+-----------------------------------------+
查看以上查询开销：SHOW PROFILE Syntax
- SHOW PROFILE [type [, type] ... ]
- [FOR QUERY n]
- [LIMIT row_count [OFFSET offset]]
- type:
- ALL
- | BLOCK IO
- | CONTEXT SWITCHES
- | CPU
- | IPC
- | MEMORY
- | PAGE FAULTS
- | SOURCE
- | SWAPS
默认显示时间信息，显示了该查询从开始到被清除各个阶段的执行时间。
- mysql> show profile;
- +----------------------+----------+
- | Status | Duration |
- +----------------------+----------+
- | starting | 0.000090 |
- | checking permissions | 0.000007 |
- | Opening tables | 0.000048 |
- | init | 0.000033 |
- | System lock | 0.000006 |
- | optimizing | 0.000018 |
- | statistics | 0.000018 |
- | preparing | 0.000015 |
- | Sorting result | 0.000006 |
- | executing | 0.000328 |
- | Sending data | 0.000016 |
- | Creating sort index | 0.000081 |
- | end | 0.000004 |
- | query end | 0.000006 |
- | closing tables | 0.000003 |
- | removing tmp table | 0.000005 |
- | closing tables | 0.000004 |
- | freeing items | 0.000068 |
- | cleaning up | 0.000017 |
- +----------------------+----------+
其他查看方法：
- mysql> show profile;
- mysql> select * from information_schema.profiling;
- mysql> select * from information_schema.profiling where query_id=6 or
- mysql> show profile; #默认显示时间信息
- mysql> show profile CPU,BLOCK IO; #(时间)加上 CPU,BLOCK IO 使用情况
- mysql> show profile for query 6; #query_id=6的(时间)信息
- mysql> show profile CPU for query 6; #query_id=6的cpu信息
- mysql> show profile CPU limit 6; #前6个状态信息(前6行)
- mysql> show profile CPU limit 6 offset 2;#第2行起前6个状态信息(前2~7行)
关闭跟踪：
- set profiling = 0;
- set profiling_history_size = 0;
参考：