利用show profiles 和 show profile查询SQL语句的资源统计

一般用于会话级，用于收集SQL语句的资源使用情况。

1.首先要设置系统变量profiling为on（作用于当前会话）

mysql> show variables like 'profiling%';
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| profiling              | OFF   |
| profiling_history_size | 15    |
+------------------------+-------+
2 rows in set (0.01 sec)

mysql> set profiling=on;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> 

2.执行SQL语句

mysql> select * from user where user_id=2222;
+---------+--------------+---------------+---------------------+
| user_id | user_name    | user_email    | created             |
+---------+--------------+---------------+---------------------+
|    2222 | bill2222 | [email protected] | 2020-02-09 12:24:32 |
+---------+--------------+---------------+---------------------+
1 row in set (0.00 sec)

3.通过show profiles查看

mysql> show profiles;
+----------+------------+---------------------------------------+
| Query_ID | Duration   | Query                                 |
+----------+------------+---------------------------------------+
|        1 | 0.00041000 | select database()                     |
|        2 | 0.00018500 | SELECT DATABASE()                     |
|        3 | 0.00382575 | show databases                        |
|        4 | 0.00040850 | show tables                           |
|        5 | 0.00106125 | show tables                           |
|        6 | 0.00211250 | desc user                             |
|        7 | 0.00031950 | SELECT * FROM USER WHERE user_id=2222 |
|        8 | 0.00019250 | SELECT DATABASE()                     |
|        9 | 0.00018200 | SELECT * FROM USER WHERE user_id=2222 |
|       10 | 0.00040700 | show databases                        |
|       11 | 0.00016275 | SELECT DATABASE()                     |
|       12 | 0.00031225 | SELECT * FROM USER WHERE user_id=2222 |
|       13 | 0.00041075 | show tables                           |
|       14 | 0.00031975 | select * from user where user_id=2222 |
+----------+------------+---------------------------------------+
14 rows in set, 1 warning (0.00 sec)

4.通过show profile for query 查看指定的SQL语句

mysql> show profile for query 14;
+----------------------+----------+
| Status               | Duration |
+----------------------+----------+
| starting             | 0.000074 |
| checking permissions | 0.000015 |
| Opening tables       | 0.000023 |
| init                 | 0.000029 |
| System lock          | 0.000013 |
| optimizing           | 0.000012 |
| statistics           | 0.000061 |
| preparing            | 0.000012 |
| executing            | 0.000005 |
| Sending data         | 0.000017 |
| end                  | 0.000005 |
| query end            | 0.000010 |
| closing tables       | 0.000009 |
| freeing items        | 0.000020 |
| cleaning up          | 0.000015 |
+----------------------+----------+
15 rows in set, 1 warning (0.00 sec)

mysql> 

6.查看SQL语句的CPU及资源情况

mysql> show profile cpu,source for query 14;
+----------------------+----------+----------+------------+-----------------------+----------------------+-------------+
| Status               | Duration | CPU_user | CPU_system | Source_function       | Source_file          | Source_line |
+----------------------+----------+----------+------------+-----------------------+----------------------+-------------+
| starting             | 0.000074 | 0.000046 |   0.000025 | NULL                  | NULL                 |        NULL |
| checking permissions | 0.000015 | 0.000008 |   0.000004 | check_access          | sql_authorization.cc |         809 |
| Opening tables       | 0.000023 | 0.000015 |   0.000008 | open_tables           | sql_base.cc          |        5753 |
| init                 | 0.000029 | 0.000019 |   0.000009 | handle_query          | sql_select.cc        |         128 |
| System lock          | 0.000013 | 0.000009 |   0.000005 | mysql_lock_tables     | lock.cc              |         330 |
| optimizing           | 0.000012 | 0.000007 |   0.000004 | optimize              | sql_optimizer.cc     |         158 |
| statistics           | 0.000061 | 0.000041 |   0.000022 | optimize              | sql_optimizer.cc     |         374 |
| preparing            | 0.000012 | 0.000007 |   0.000003 | optimize              | sql_optimizer.cc     |         482 |
| executing            | 0.000005 | 0.000003 |   0.000002 | exec                  | sql_executor.cc      |         126 |
| Sending data         | 0.000017 | 0.000011 |   0.000005 | exec                  | sql_executor.cc      |         202 |
| end                  | 0.000005 | 0.000003 |   0.000003 | handle_query          | sql_select.cc        |         206 |
| query end            | 0.000010 | 0.000007 |   0.000003 | mysql_execute_command | sql_parse.cc         |        4956 |
| closing tables       | 0.000009 | 0.000006 |   0.000003 | mysql_execute_command | sql_parse.cc         |        5009 |
| freeing items        | 0.000020 | 0.000013 |   0.000007 | mysql_parse           | sql_parse.cc         |        5622 |
| cleaning up          | 0.000015 | 0.000010 |   0.000005 | dispatch_command      | sql_parse.cc         |        1931 |
+----------------------+----------+----------+------------+-----------------------+----------------------+-------------+
15 rows in set, 1 warning (0.00 sec)

mysql> 
还可以使用下面的语句查看更多的信息：
mysql> show profile all for query 14;