MySQL 普通查询日志 和 慢查询日志介绍

Posted 2020-08-09

1. 普通查询日志(general query log)介绍

普通查询日志记录客户端连接信息和执行的sql语句信息

1.1 临时开启general_log日志开关

mysql> show variables like ‘general_log%‘; +------------------+---------------------------+ | Variable_name    | Value                     | +------------------+---------------------------+ | general_log      | OFF                       |            -> 默认为关闭状态 | general_log_file | /data/3306/data/node1.log | +------------------+---------------------------+ mysql> set global general_log = ON; mysql> set global general_log_file = "/data/3306/data/general_90root.log"; mysql> show variables like ‘general_log%‘; +------------------+------------------------------------+ | Variable_name    | Value                              | +------------------+------------------------------------+ | general_log      | ON                                 | | general_log_file | /data/3306/data/general_90root.log | +------------------+------------------------------------+ ## 以上配置临时生效

1.2 永久开启general_log日志开关

[[email protected] ~]# cat /data/3306/my.cnf [mysqld] character_set_server = utf8 general_log = ON general_log_file = "/data/3306/data/general_90root.log";  [[email protected] ~]# /data/3306/mysql restart [[email protected] ~]#  mysql -uroot -p90root3306 -S /data/3306/mysql.sock mysql> show variables like ‘general_log%‘; +------------------+-------------------------------------+ | Variable_name    | Value                               | +------------------+-------------------------------------+ | general_log      | ON                                  | | general_log_file | /data/3306/data/general_90root.log  | +------------------+-------------------------------------+ [[email protected] ~]# tail -f /data/3306/data/general_90root.log 160723  4:54:49     4 Query     show databases mysql> show databases; +--------------------+ | Database           | +--------------------+ | information_schema | | 90_root            | | 90root             | | 90root_gbk         | | 90root_test        | | ab                 | | mysql              | | performance_schema | | test               | | test_sz            | +--------------------+

企业里一般是关闭的, 因为性能的问题

2. 慢查询日志(slow query log)介绍

慢查询日志只记录执行时间超出指定值的sql语句

慢查询的设置对于数据库sql的优化非常重要

[[email protected] ~]# cat /data/3306/my.cnf [mysqld] long_query_time     = 1                 -> sql执行语句超过1秒记录到慢查询日志 slow-query-log-file   = /data/3306/slow.log     -> 慢查询日志文件路径 log_queries_not_using_indexes           -> 没有走索引的sql语句记录到慢查询日志 [[email protected] ~]# /data/3306/mysql restart

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