MySQL性能分析工具profiling
MySQL性能分析工具profiling
MySQL数据库中，可以通过配置profiling参数来启用SQL性能分析，找出当前SQL瓶颈，进而优化、调整sql语句。
profiling参数开启后，后续执行的SQL语句都将记录其资源开销，诸如IO，IPC，CPU，Memory等等。
用法：
mysql> help profile
Name:'SHOW PROFILE'
Description:
Syntax:
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
Profiling变量默认值为0（off），可以通过设置profiling为0或ON开启
mysql>select @@profiling;
+-------------+
|@@profiling |
+-------------+
| 0 |
+-------------+
1 row inset (0.03 sec)
mysql>show variables like '%profil%';
+------------------------+-------+
|Variable_name | Value |
+------------------------+-------+
|profiling | OFF |
|profiling_history_size | 15 |
+------------------------+-------+
2 rows inset (0.00 sec)
profiling：设置是否开启SQL性能剖析
profiling_history_size：设置是SQL性能剖析缓存的记录数
mysql>set profiling=1;
Query OK,0 rows affected (0.03 sec)
mysql>show variables like '%profil%';
+------------------------+-------+
|Variable_name | Value |
+------------------------+-------+
|profiling | ON |
|profiling_history_size | 15 |
+------------------------+-------+
2 rows inset (0.00 sec)
mysql>show variables like 'profiling_history_size';
+------------------------+-------+
|Variable_name | Value |
+------------------------+-------+
|profiling_history_size | 15 |
+------------------------+-------+
1 row inset (0.00 sec)
show profiles:返回一个列表,显示最近发送到服务器上执行的语句的资源使用情况.
显示的记录数由变量“profiling_history_size”控制,默认15条，最大值为100，可以手动设置该参数值。
mysql>set profiling_history_size = 30;
Query OK,0 rows affected (0.00 sec)
mysql>show variables like '%profil%';
+------------------------+-------+
|Variable_name | Value |
+------------------------+-------+
|profiling | ON |
|profiling_history_size | 30 |
+------------------------+-------+
2 rows inset (0.00 sec)
选项注释：
type:
ALL ：显示所有信息
|BLOCK IO ：块设备IO输入输出次数
|CONTEXT SWITCHES：上下文切换相关开销
|CPU：用户和系统的CPU使用情况
|IPC：显示发送和接收消息的相关消耗
|MEMORY：内存消耗情况（该版本is not currently implemented）
|PAGE FAULTS：显示主要和次要页面故障相关的开销
|SOURCE：显示和Source_function,Source_file,Source_line相关的开销信息
|SWAPS：显示交换次数相关的开销
Profilingis enabled per session. When a session ends, itsprofiling
information is lost.
注意：profiling被应用在每一个会话中，当前会话关闭后，profiling统计的信息将丢失。
用法示例：
mysql>use mydb
mysql>drop table if exists t4;
Query OK,0 rows affected, 1 warning (0.00 sec)
mysql>create table cid(id int);
Query OK,0 rows affected (0.05 sec)
mysql>show profiles;
+----------+------------+----------------------------------------------+
| Query_ID| Duration |Query |
+----------+------------+----------------------------------------------+
| 1 | 0.00061900 | show variables like '%profil%' |
| 2 | 0.00061800 | show variables like 'profiling_history_size'|
| 3 | 0.00010600 | set profiling_history_size = 30 |
| 4 | 0.00078200 | show variables like '%profil%' |
| 5 | 0.00018800 | SELECT DATABASE() |
| 6 | 0.00050400 | show databases |
| 7 | 0.00032200 | show tables |
| 8 | 0.00027300 | drop table if exists t4 |
| 9 | 0.04367500 | create table cid(id int) |
+----------+------------+----------------------------------------------+
9 rows inset (0.00 sec)
mysql>show profile; -->默认会打开上一个语句的开销信息
+----------------------+----------+
|Status | Duration |
+----------------------+----------+
|starting | 0.000074 |
| checkingpermissions | 0.000083 |
| creatingtable | 0.043427 |
| Aftercreate | 0.000014 |
| queryend | 0.000003 |
| freeingitems | 0.000068 |
| loggingslow query |0.000004 |
| cleaningup | 0.000002 |
+----------------------+----------+
8 rows inset (0.02 sec)
mysql>show profile for query 9; -->获取指定查询的开销
+----------------------+----------+
|Status | Duration |
+----------------------+----------+
|starting | 0.000074 |
| checkingpermissions | 0.000083 |
| creatingtable | 0.043427 |
| Aftercreate | 0.000014 |
| queryend | 0.000003 |
| freeingitems | 0.000068 |
| loggingslow query |0.000004 |
| cleaningup | 0.000002 |
+----------------------+----------+
8 rows inset (0.00 sec)
-->查看特定部分的开销，如CPU,SWAPS,BLOCK IO的开销
mysql>show profile CPU,SWAPS,BLOCK IO for query 9;
+----------------------+----------+----------+------------+--------------+---------------+-------+
|Status |Duration | CPU_user | CPU_system | Block_ops_in | Block_ops_out |Swaps |
+----------------------+----------+----------+------------+--------------+---------------+-------+
|starting | 0.000074 | 0.000000 | 0.000000 | 0| 0 | 0 |
| checkingpermissions | 0.000083 | 0.000000 | 0.000000 | 0 | 0 | 0 |
| creatingtable | 0.043427 | 0.009998 | 0.017997 | 0 | 256 | 0 |
| Aftercreate | 0.000014 | 0.000000 | 0.000000 | 0 | 0 | 0 |
| queryend | 0.000003 | 0.000000 | 0.000000 | 0 | 0 | 0 |
| freeingitems | 0.000068 | 0.000000 | 0.000000 | 0 | 0 | 0 |
| loggingslow query |0.000004 | 0.000000 | 0.000000 | 0 | 0 | 0 |
| cleaningup | 0.000002 | 0.000000 | 0.000000 | 0 | 0 | 0 |
+----------------------+----------+----------+------------+--------------+---------------+-------+
8 rows inset (0.00 sec)
mysql>show profile ALL for query 9;
+----------------------+----------+----------+------------+-------------------+---------------------+--------------+---------------+---------------+-------------------+-------------------+-------------------+-------+------------------+--------------+-------------+
|Status | Duration | CPU_user | CPU_system | Context_voluntary |Context_involuntary | Block_ops_in | Block_ops_out | Messages_sent| Messages_received | Page_faults_major | Page_faults_minor | Swaps| Source_function |Source_file | Source_line |
+----------------------+----------+----------+------------+-------------------+---------------------+--------------+---------------+---------------+-------------------+-------------------+-------------------+-------+------------------+--------------+-------------+
|starting | 0.000074 | 0.000000 | 0.000000 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | 0 | NULL |NULL | NULL |
| checkingpermissions | 0.000083 | 0.000000 | 0.000000 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 4 | 0 | unknown function | sql_parse.cc | 5369 |
| creatingtable | 0.043427 | 0.009998 | 0.017997 | 17 | 0 | 0 | 256 | 0 | 0 | 0 | 26 | 0 |unknown function | sql_table.cc | 3975 |
| Aftercreate | 0.000014 | 0.000000 | 0.000000 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0| 0 | unknown function | sql_table.cc | 4062 |
| queryend | 0.000003 | 0.000000 | 0.000000 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0| 0 | unknown function | sql_parse.cc | 5133 |
| freeingitems | 0.000068 | 0.000000 | 0.000000 | 0 | 0 | 0 | 0 | 0 | 0 | 0| 0 | 0 | unknown function | sql_parse.cc | 6157 |
| loggingslow query |0.000004 | 0.000000 | 0.000000 | 0 | 0 | 0 | 0 | 0 | 0 | 0| 0 | 0 | unknown function | sql_parse.cc | 1745 |
| cleaningup | 0.000002 | 0.000000 | 0.000000 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | unknown function | sql_parse.cc | 1713 |
+----------------------+----------+----------+------------+-------------------+---------------------+--------------+---------------+---------------+-------------------+-------------------+-------------------+-------+------------------+--------------+-------------+
8 rows inset (0.00 sec)