mysql中profile的使用

1.profile在mysql5.0.37及其以上版本中可用

2.查看profile是否可用
SELECT @@profiling;
来查看是否已经启用profile，如果profilng值为0，可以通过
SET profiling = 1;
启用
mysql>select count(*) from roi_summary;

然后show profiles查看如下：


+----------------+------------+----------------------------------+
| Query_ID       | Duration   | Query                            |
+----------------+------------+----------------------------------+
|        1       | 0.00021500 | select @@profiling               |
|        2       | 0.05522700 | select count(*) from roi_summary |
+----------------+------------+----------------------------------+

其中ID为5的语句是刚执行的查询语句
mysql> show profile for query 2;
分析其性能
+--------------------------------+----------+
| Status                         | Duration |
+--------------------------------+----------+
| (initialization)               | 0.000004 |
| checking query cache for query | 0.000044 |
| Opening tables                 | 0.000012 |
| System lock                    | 0.000017 |
| Table lock                     | 0.00003  |
| init                           | 0.000013 |
| optimizing                     | 0.000008 |
| statistics                     | 0.000013 |
| preparing                      | 0.000011 |
| executing                      | 0.000006 |
| Sending data                   | 0.747313 |
| end                            | 0.000014 |
| query end                      | 0.000006 |
| storing result in query cache  | 0.000006 |
| freeing items                  | 0.000012 |
| closing tables                 | 0.000009 |
| logging slow query             | 0.000183 |
+--------------------------------+----------+
17 rows in set (0.00 sec)

#查看cpu io memory swaps
mysql> show profile cpu,block io,memory,swaps for query 2;


注意:
1.profile是用户级变量,每次都得重新启用
2.需在终端使用,在phpmyadmin下无效