MySQL Profiling 的使用

MySQL 的 Query Profiler 是一个使用非常方便的 Query 诊断分析工具，通过该工具可以获取一条Query 在整个执行过程中多种资源的消耗情况，如 CPU，IO，IPC，SWAP 等，以及发生的 PAGE FAULTS，CONTEXT SWITCHE 等等，同时还能得到该 Query 执行过程中 MySQL 所调用的各个函数在源文件中的位置。1、开启profile 参数

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

2）获取系统中保存的所有 Query 的 profile 概要信息

mysql> show profiles;
+----------+------------+---------------------------------+
| Query_ID | Duration   | Query                           |
+----------+------------+---------------------------------+
|        1 | 0.00081200 | show tables                     |
|        2 | 0.08324000 | select * from test.shop         |
|        3 | 0.03196700 | select * from test.pet          |
|        4 | 0.04903500 | select * from SESSION_VARIABLES |
+----------+------------+---------------------------------+
4 rows in set, 1 warning (0.00 sec)

3）针对单个 Query 获取详细的 profile 信息。

mysql> show profile cpu,block io for query 4;
+----------------------+----------+----------+------------+--------------+---------------+
| Status               | Duration | CPU_user | CPU_system | Block_ops_in | Block_ops_out |
+----------------------+----------+----------+------------+--------------+---------------+
| starting             | 0.000055 | 0.000000 |   0.000000 |            0 |             0 |
| checking permissions | 0.000009 | 0.000000 |   0.000000 |            0 |             0 |
| Opening tables       | 0.000045 | 0.000000 |   0.000000 |            0 |             0 |
| init                 | 0.000016 | 0.000000 |   0.000000 |            0 |             0 |
| System lock          | 0.000007 | 0.000000 |   0.000000 |            0 |             0 |
| optimizing           | 0.000005 | 0.000000 |   0.000000 |            0 |             0 |
| statistics           | 0.000012 | 0.000000 |   0.000000 |            0 |             0 |
| preparing            | 0.000012 | 0.000000 |   0.000000 |            0 |             0 |
| executing            | 0.048090 | 0.004000 |   0.001000 |            0 |             0 |
| Sending data         | 0.000564 | 0.000000 |   0.000000 |            0 |             0 |
| end                  | 0.000013 | 0.000000 |   0.000000 |            0 |             0 |
| query end            | 0.000007 | 0.000000 |   0.000000 |            0 |             0 |
| closing tables       | 0.000004 | 0.000000 |   0.000000 |            0 |             0 |
| removing tmp table   | 0.000128 | 0.000999 |   0.000000 |            0 |             0 |
| closing tables       | 0.000010 | 0.000000 |   0.000000 |            0 |             0 |
| freeing items        | 0.000036 | 0.000000 |   0.000000 |            0 |             0 |
| cleaning up          | 0.000022 | 0.000000 |   0.000000 |            0 |             0 |
+----------------------+----------+----------+------------+--------------+---------------+
17 rows in set, 1 warning (0.05 sec)

SHOW PROFILE Syntax

SHOW PROFILE [[code]type

[,

type

] ... ][FOR QUERY

n

][LIMIT

row_count

[OFFSET

offset

]]

type

:ALL| BLOCK IO| CONTEXT SWITCHES (CPU从一个线程切换到另外一个线程，需要保存当前任务的运行环境，恢复将要运行任务的运行环境，必然带来性能 消耗)| CPU| IPC| MEMORY| PAGE FAULTS| SOURCE 显示源代码中的函数的名称，连同函数所在文件的行号和名字| SWAPS[/code]相关的几个参数：

mysql> show variables like '%profil%';+------------------------+-------+| Variable_name          | Value |+------------------------+-------+| have_profiling         | YES   | 该版本支持profile 功能| profiling              | ON    | 开启 profile 功能| profiling_history_size | 15    | 保留profile statement 的数量，最大100，如果设置为0 ，相当于关闭profile 功能+------------------------+-------+