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要使用该功能，mysql的版本必须在5.0.37版本以上。否则只能使用explain 的方式来检查。

profiling 功能可以了解到cpu io 等更详细的信息。

show profile 的格式如下：

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

 

默认方式下该功能是关闭的：

 mysql>select @@profiling;

+-------------+

| @@profiling |

+-------------+

|           0 |

+-------------+

1 row in set (0.00 sec)

 

打开功能

mysql>set profiling=1;

 

+-------------+

| @@profiling |

+-------------+

|           1 |

+-------------+

1 row in set (0.00 sec)

 

输入需要执行的sql 语句：

mysql>select count(*) from sysuser;

mysql>select count(*) from sysuser;

 

mysql> show profiles/G;

*************************** 1. row ***************************

Query_ID: 1

Duration: 0.00007550

   Query: select count(*) from sysuser

1 row in set (0.00 sec)

 

通过指定的Query_ID 来查询指定的sql语句的执行信息：

mysql> show profile for query 1;

+--------------------------------+----------+

| Status                         | Duration |

+--------------------------------+----------+

| starting                       | 0.000028 |

| checking query cache for query | 0.000008 |

| checking privileges on cached  | 0.000009 |

| sending cached result to clien | 0.000023 |

| logging slow query             | 0.000004 |

| cleaning up                    | 0.000003 |

+--------------------------------+----------+

6 rows in set (0.00 sec)

 

mysql> show profile cpu,block io for query 1;

+--------------------------------+----------+----------+------------+--------------+---------------+

| Status                         | Duration | CPU_user | CPU_system | Block_ops_in | Block_ops_out |

+--------------------------------+----------+----------+------------+--------------+---------------+

| starting                       | 0.000028 |     NULL |       NULL |         NULL |          NULL |

| checking query cache for query | 0.000008 |     NULL |       NULL |         NULL |          NULL |

| checking privileges on cached  | 0.000009 |     NULL |       NULL |         NULL |          NULL |

| sending cached result to clien | 0.000023 |     NULL |       NULL |         NULL |          NULL |

| logging slow query             | 0.000004 |     NULL |       NULL |         NULL |          NULL |

| cleaning up                    | 0.000003 |     NULL |       NULL |         NULL |          NULL |

+--------------------------------+----------+----------+------------+--------------+---------------+

6 rows in set (0.00 sec)

 

如果不带for 参数则指列出最后一条语句的profile 信息：

mysql> show profile cpu,block io for query 1;

+--------------------------------+----------+----------+------------+--------------+---------------+

| Status                         | Duration | CPU_user | CPU_system | Block_ops_in | Block_ops_out |

+--------------------------------+----------+----------+------------+--------------+---------------+

| starting                       | 0.000028 |     NULL |       NULL |         NULL |          NULL |

| checking query cache for query | 0.000008 |     NULL |       NULL |         NULL |          NULL |

| checking privileges on cached  | 0.000009 |     NULL |       NULL |         NULL |          NULL |

| sending cached result to clien | 0.000023 |     NULL |       NULL |         NULL |          NULL |

| logging slow query             | 0.000004 |     NULL |       NULL |         NULL |          NULL |

| cleaning up                    | 0.000003 |     NULL |       NULL |         NULL |          NULL |

+--------------------------------+----------+----------+------------+--------------+---------------+

6 rows in set (0.00 sec)

关闭参数：

mysql> set profiling=0

 

+---------------+-------+

| Variable_name | Value |

+---------------+-------+

| profiling     | OFF   |

+---------------+-------+

1 row in set (0.00 sec)