本节内容&＃xff1a;
显示SQL语句执行时间
MySQL 的 SQL 语法调整主要使用 EXPLAIN&＃xff0c;不过该命令无法获取详细的 Ram(Memory)/CPU 等使用量.
于 MySQL 5.0.37 以上开始支持 MySQL Query Profiler, 可以查詢到此 SQL执行多长时间&＃xff0c;并 並看出 CPU/Memory 使用量, 执行过程中 System lock, Table lock 花多少时间等.
效能分析主要分下述三种:
Bottleneck analysis - focuses on answering the questions: What is my database server waiting on; what is a user connection waiting on; what is a piece of SQL code waiting on?
Workload analysis - examines the server and who is logged on to determine the resource usage and activity of each.
Ratio-based analysis - utilizes a number of rule-of-thumb ratios to gauge performance of a database, user connection, or piece of code.
MySQL Query Profile 使用方法
启动&＃xff1a;
mysql> set profiling&＃61;1; # 此命令于 MySQL 会于 information_schema 的 database 建立一个 PROFILING 的 table 来记录.
SQL profiles show
mysql> show profiles; # 从启动之后所有语法及使用时间, 含错误语法都会记录.
例如:
代码示例:
(root&＃64;jbxue.com) [test]> show profiles; # 注意 Query_ID, 下面执行时间统计等, 都是依 Query_ID 在记录
&＃43;----------&＃43;------------&＃43;---------------------------&＃43;
| Query_ID | Duration | Query |
&＃43;----------&＃43;------------&＃43;---------------------------&＃43;
| 1 | 0.00090400 | show profile for query 1 |
| 2 | 0.00008700 | select * from users |
| 3 | 0.00183800 | show tables |
| 4 | 0.00027600 | mysql> show profiles |
&＃43;----------&＃43;------------&＃43;---------------------------&＃43;
1&＃xff0c;查询所有花费时间加总
代码示例:
mysql> select sum(duration) from information_schema.profiling where query_id&＃61;1; # Query ID &＃61; 1
&＃43;---------------&＃43;
| sum(duration) |
&＃43;---------------&＃43;
| 0.000447 |
&＃43;---------------&＃43;
2&＃xff0c;查询各执行阶段花费多少时间
代码示例:
mysql> show profile for query 1; # Query ID &＃61; 1
&＃43;--------------------&＃43;------------&＃43;
| Status | Duration |
&＃43;--------------------&＃43;------------&＃43;
| (initialization) | 0.00006300 |
| Opening tables | 0.00001400 |
| System lock | 0.00000600 |
| Table lock | 0.00001000 |
| init | 0.00002200 |
| optimizing | 0.00001100 |
| statistics | 0.00009300 |
| preparing | 0.00001700 |
| executing | 0.00000700 |
| Sending data | 0.00016800 |
| end | 0.00000700 |
| query end | 0.00000500 |
| freeing items | 0.00001200 |
| closing tables | 0.00000800 |
| logging slow query | 0.00000400 |
&＃43;--------------------&＃43;------------&＃43;
3&＃xff0c;查询各执行阶段花费的各种资源列表
代码示例:
mysql> show profile cpu for query 1; # Query ID &＃61; 1
&＃43;--------------------------------&＃43;----------&＃43;----------&＃43;------------&＃43;
| Status | Duration | CPU_user | CPU_system |
&＃43;--------------------------------&＃43;----------&＃43;----------&＃43;------------&＃43;
| (initialization) | 0.000007 | 0 | 0 |
| checking query cache for query | 0.000071 | 0 | 0 |
| Opening tables | 0.000024 | 0 | 0 |
| System lock | 0.000014 | 0 | 0 |
| Table lock | 0.000055 | 0.001 | 0 |
| init | 0.000036 | 0 | 0 |
| optimizing | 0.000013 | 0 | 0 |
| statistics | 0.000021 | 0 | 0 |
| preparing | 0.00002 | 0 | 0 |
| executing | 0.00001 | 0 | 0 |
| Sending data | 0.015072 | 0.011998 | 0 |
| end | 0.000021 | 0 | 0 |
| query end | 0.000011 | 0 | 0 |
| storing result in query cache | 0.00001 | 0 | 0 |
| freeing items | 0.000018 | 0 | 0 |
| closing tables | 0.000019 | 0 | 0 |
| logging slow query | 0.000009 | 0 | 0 |
&＃43;--------------------------------&＃43;----------&＃43;----------&＃43;------------&＃43;
mysql> show profile IPC for query 1;
&＃43;--------------------------------&＃43;----------&＃43;---------------&＃43;-------------------&＃43;
| Status | Duration | Messages_sent | Messages_received |
&＃43;--------------------------------&＃43;----------&＃43;---------------&＃43;-------------------&＃43;
| (initialization) | 0.000007 | 0 | 0 |
| checking query cache for query | 0.000071 | 0 | 0 |
| Opening tables | 0.000024 | 0 | 0 |
| System lock | 0.000014 | 0 | 0 |
| Table lock | 0.000055 | 0 | 0 |
| init | 0.000036 | 0 | 0 |
| optimizing | 0.000013 | 0 | 0 |
| statistics | 0.000021 | 0 | 0 |
| preparing | 0.00002 | 0 | 0 |
| executing | 0.00001 | 0 | 0 |
| Sending data | 0.015072 | 0 | 0 |
| end | 0.000021 | 0 | 0 |
| query end | 0.000011 | 0 | 0 |
| storing result in query cache | 0.00001 | 0 | 0 |
| freeing items | 0.000018 | 0 | 0 |
| closing tables | 0.000019 | 0 | 0 |
| logging slow query | 0.000009 | 0 | 0 |
&＃43;--------------------------------&＃43;----------&＃43;---------------&＃43;-------------------&＃43;
4&＃xff0c;其它属性列表
ALL - displays all information
BLOCK IO - displays counts for block input and output operations
CONTEXT SWITCHES - displays counts for voluntary and involuntary context switches
IPC - displays counts for messages sent and received
MEMORY - is not currently implemented
PAGE FAULTS - displays counts for major and minor page faults
SOURCE - displays the names of functions from the source code, together with the name and line number of the file in which the function occurs
SWAPS - displays swap counts
5&＃xff0c;设定 Profiling 存的 Size&＃xff1a;
代码示例:
mysql> show variables where variable_name&＃61;&＃39;profiling_history_size&＃39;; # 预设是 15笔
关闭&＃xff1a;
代码示例:
mysql> set profiling&＃61;0;
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