标签：div 进程 warning rom str his pen 影响 variable
MySQL性能分析show profiles
show profile 和 show profiles 语句可以展示当前会话(退出session后,profiling重置为0) 中执行语句的资源使用情况。
Profiling 功能由MySQL会话变量 : profiling控制,默认是OFF.关闭状态。select @@profiling; 或者show variables like ‘%profi%‘；
mysql> select @@profiling; +-------------+ | @@profiling | +-------------+ | 0 | +-------------+
Profiling是针对进程(process)而非线程(threads),因此运行在服务器上的其他服务进程可能会影响分析结果。Profiling 信息收集依赖于调用 系统方法 getrusage().因此Windows系统不适用。
开启Profiling功能：
mysql> set profiling = 1; Query OK, 0 rows affected, 1 warning (0.00 sec)
退出会话后，Profiling功能自动关闭。
语句使用：
show profiles :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。
mysql> show profiles; +----------+------------+-------------------------------+ | Query_ID | Duration | Query | +----------+------------+-------------------------------+ | 1 | 0.00371475 | show variables like ‘%profi%‘ | | 2 | 0.00005700 | show prifiles | | 3 | 0.00011775 | SELECT DATABASE() | | 4 | 0.00034875 | select * from student | +----------+------------+-------------------------------+
show profile: 展示最近一条语句执行的详细资源占用信息,默认显示 Status和Duration两列
mysql> show profile; +----------------------+----------+ | Status | Duration | +----------------------+----------+ | starting | 0.000054 | | checking permissions | 0.000007 | | Opening tables | 0.000116 | | init | 0.000019 | | System lock | 0.000009 | | optimizing | 0.000004 | | statistics | 0.000011 | | preparing | 0.000010 | | executing | 0.000002 | | Sending data | 0.000061 | | end | 0.000005 | | query end | 0.000006 | | closing tables | 0.000006 | | freeing items | 0.000031 | | cleaning up | 0.000010 | +----------------------+----------+
show profile 还可根据 show profiles 列表中的 Query_ID ,选择显示某条记录的性能分析信息。
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 }
实例：
Examples: mysql> SELECT @@profiling; +-------------+ | @@profiling | +-------------+ | 0 | +-------------+ 1 row in set (0.00 sec) mysql> SET profiling = 1; Query OK, 0 rows affected (0.00 sec) mysql> DROP TABLE IF EXISTS t1; Query OK, 0 rows affected, 1 warning (0.00 sec) mysql> CREATE TABLE T1 (id INT); Query OK, 0 rows affected (0.01 sec) mysql> SHOW PROFILES; +----------+----------+--------------------------+ | Query_ID | Duration | Query | +----------+----------+--------------------------+ | 0 | 0.000088 | SET PROFILING = 1 | | 1 | 0.000136 | DROP TABLE IF EXISTS t1 | | 2 | 0.011947 | CREATE TABLE t1 (id INT) | +----------+----------+--------------------------+ 3 rows in set (0.00 sec) mysql> SHOW PROFILE; +----------------------+----------+ | Status | Duration | +----------------------+----------+ | checking permissions | 0.000040 | | creating table | 0.000056 | | After create | 0.011363 | | query end | 0.000375 | | freeing items | 0.000089 | | logging slow query | 0.000019 | | cleaning up | 0.000005 | +----------------------+----------+ 7 rows in set (0.00 sec) mysql> SHOW PROFILE FOR QUERY 1; +--------------------+----------+ | Status | Duration | +--------------------+----------+ | query end | 0.000107 | | freeing items | 0.000008 | | logging slow query | 0.000015 | | cleaning up | 0.000006 | +--------------------+----------+ 4 rows in set (0.00 sec) mysql> SHOW PROFILE CPU FOR QUERY 2; +----------------------+----------+----------+------------+ | Status | Duration | CPU_user | CPU_system | +----------------------+----------+----------+------------+ | checking permissions | 0.000040 | 0.000038 | 0.000002 | | creating table | 0.000056 | 0.000028 | 0.000028 | | After create | 0.011363 | 0.000217 | 0.001571 | | query end | 0.000375 | 0.000013 | 0.000028 | | freeing items | 0.000089 | 0.000010 | 0.000014 | | logging slow query | 0.000019 | 0.000009 | 0.000010 | | cleaning up | 0.000005 | 0.000003 | 0.000002 | +----------------------+----------+----------+------------+ 7 rows in set (0.00 sec)
mysql性能分析show profile/show profiles
标签：div 进程 warning rom str his pen 影响 variable
原文地址：https://www.cnblogs.com/jkin/p/10255070.html
