Mysql运用profile剖析sql开支的代码【MySQL教程】,mysql

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Mysql运用profile理会sql开支

1.运用之前先检察当前数据库的版本信息,低版本没法运用.
    show version();  或许 show variables like '%version%'
2.检察profiling
    show variables like '%profil%'    ;

    result:
        +------------------------+-------+  
        | Variable_name          | Value |  
        +------------------------+-------+  
        | have_profiling         | YES   |   --只读变量，用于掌握是不是由体系变量开启或禁用profiling  
        | profiling              | OFF   |   --开启SQL语句理会功用  
        | profiling_history_size | 15    |   --设置保存profiling的数量，缺省为15，局限为0至100，为0时将禁用p

    show profiles; 检察是不是开启,结果同上.
3.检察运用说明 
    help profile;
4.开启profile
    set profiling=1; 赋值时刻不要有过剩的空格.
5.运转sql,检察对应的profile
    select * from test ;
    show profiles;            

    result:
    +----------+------------+--------------------------------------------------------------------------------------------------------------------------+
    | Query_ID | Duration   | Query                                                                                                                    |
    +----------+------------+--------------------------------------------------------------------------------------------------------------------------+
    |       28 | 0.00033575 | select * from test                                                                                        |
    +----------+------------+--------------------------------------------------------------------------------------------------------------------------+

    理会sql机能,理会的时刻能够加上对应的开支字段
    show profile [cpu,io][all] for query 28 ;

    show profile for query 28 ;

    +----------------------+----------+
    | Status               | Duration |
    +----------------------+----------+
    | starting             | 5.7E-5   |
    | checking permissions | 7E-6     |
    | Opening tables       | 1.7E-5   |
    | init                 | 2.3E-5   |
    | System lock          | 8E-6     |
    | optimizing           | 5E-6     |
    | statistics           | 1.1E-5   |
    | preparing            | 9E-6     |
    | executing            | 3E-6     |
    | Sending data         | 8.8E-5   |
    | end                  | 5E-6     |
    | query end            | 6E-6     |
    | closing tables       | 5E-6     |
    | freeing items        | 7.8E-5   |
    | cleaning up          | 1.5E-5   |
    +----------------------+----------+
6.封闭
    set profiling=off;

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