Mysql教程性能跟踪语句.doc

原文链接：/u/29134/showart_480834.html MYSQL5.0家族提供的性能跟踪器确实很爽。要注意两点。1、不过版本要在5.0.37之后手册上介绍：(SHOW PROFILES and SHOW PROFILE were added in MySQL 5.0.37. )ImportantPlease note that the SHOW PROFILE and SHOW PROFILES functionality is part of the MySQL 5.0 Community Server only. 2、变量profiling是用户变量，每次都得重新启用。以下是我做的一些实验。数据很明显，就不多解释了。mysql use testDatabase changedmysql set profiling=1;Query OK, 0 rows affected (0.00 sec)mysql show tables;+----------------+| Tables_in_test |+----------------+| bag_item | | bag_user | | score | | t | +----------------+4 rows in set (0.03 sec)mysql select count(*) from t;+----------+| count(*) |+----------+| 2097152 | +----------+1 row in set (0.74 sec)mysql show profiles;+----------+------------+------------------------+| Query_ID | Duration?? | Query????????????????? |+----------+------------+------------------------+|??????? 1 | 0| show tables??????????? | |??????? 2 | 0|?select?count(*) from t | +----------+------------+------------------------+2 rows in set (0.00 sec)mysql show profile for query 2;+--------------------------------+----------+| Status???????????????????????? | Duration |+--------------------------------+----------+| (initialization)?????????????? | 0.000004 | | checking query cache for query | 0.000044 | | Opening tables???????????????? | 0.000012 | | System lock??????????????????? | 0.000017 | | Table lock???????????????????? | 0.00003? | | init?????????????????????????? | 0.000013 | | optimizing???????????????????? | 0.000008 | | statistics???????????????????? | 0.000013 | | preparing????????????????????? | 0.000011 | | executing????????????????????? | 0.000006 | | Sending data?????????????????? | 0.747313 | | end??????????????????????????? | 0.000014 | | query end????????????????????? | 0.000006 | | storing result in query cache? | 0.000006 | | freeing items????????????????? | 0.000012 | | closing tables???????????????? | 0.000009 | | loggi