MySQLSQL剖析(SQLprofile) - 数据库编程

la]> show profiles; +----------+------------+--------------------------------+ | Query_ID | Duration | Query | +----------+------------+--------------------------------+ | 1 | 0.00253600 | show variables like '%profil%' | | 2 | 0.00138150 | select count(*) from customer | +----------+------------+--------------------------------+ 2 rows in set, 1 warning (0.01 sec) --我们看到有2个warning，之前一个，现在一个 root@localhost[sakila]> show warnings; --下面的结果表明SHOW PROFILES将来会被Performance Schema替换掉 +---------+------+--------------------------------------------------------------------------------------------------------------+ | Level | Code | Message | +---------+------+--------------------------------------------------------------------------------------------------------------+ | Warning | 1287 | 'SHOW PROFILES' is deprecated and will be removed in a future release. Please use Performance Schema instead | +---------+------+--------------------------------------------------------------------------------------------------------------+

3、获取SQL语句的开销信息

--可以直接使用show profile来查看上一条SQL语句的开销信息
--注，show profile之类的语句不会被profiling，即自身不会产生Profiling
--我们下面的这个show profile查看的是show warnings产生的相应开销
root@localhost[sakila]> show profile;  
+----------------+----------+
| Status         | Duration |
+----------------+----------+
| starting       | 0.000141 |
| query end      | 0.000058 |
| closing tables | 0.000014 |
| freeing items  | 0.001802 |
| cleaning up    | 0.000272 |
+----------------+----------+

--如下面的查询show warnings被添加到profiles
root@localhost[sakila]> show profiles;
+----------+------------+--------------------------------+
| Query_ID | Duration   | Query                          |
+----------+------------+--------------------------------+
|        1 | 0.00253600 | show variables like '%profil%' |
|        2 | 0.00138150 | select count(*) from customer  |
|        3 | 0.00228600 | show warnings                  |
+----------+------------+--------------------------------+

--获取指定查询的开销
root@localhost[sakila]>




 show profile for query 2;
+----------------------+----------+
| Status               | Duration |
+----------------------+----------+
| starting             | 0.000148 |
| checking permissions | 0.000014 |
| Opening tables       | 0.000047 |
| init                 | 0.000023 |
| System lock          | 0.000035 |
| optimizing           | 0.000012 |
| statistics           | 0.000019 |
| preparing            | 0.000014 |
| executing            | 0.000006 |
| Sending data         | 0.000990 |
| end                  | 0.000010 |
| query end            | 0.000011 |
| closing tables       | 0.000010 |
| freeing items        | 0.000016 |
| cleaning up          | 0.000029 |
+----------------------+----------+

--查看特定部分的开销，如下为CPU部分的开销
root@localhost[sakila]> show profile cpu for query 2 ;
+----------------------+----------+----------+------------+
| Status               | Duration | CPU_user | CPU_system |
+----------------------+----------+----------+------------+
| starting             | 0.000148 | 0.000000 |   0.000000 |
| checking permissions | 0.000014 | 0.000000 |   0.000000 |
| Opening tables       | 0.000047 | 0.000000 |   0.000000 |
| init                 | 0.000023 | 0.000000 |   0.000000 |
| System lock          | 0.000035 | 0.000000 |   0.000000 |
| optimizing           | 0.000012 | 0.000000 |   0.000000 |
| statistics           | 0.000019 | 0.000000 |   0.000000 |
| preparing            | 0.000014 | 0.000000 |   0.000000 |
| executing            | 0.000006 | 0.000000 |   0.000000 |
| Sending data         | 0.000990 | 0.001000 |   0.000000 |
| end                  | 0.000010 | 0.000000 |   0

MySQLSQL剖析(SQLprofile)(二)