1、查询执行速度慢的sql语句

• 查看当前“慢语句”标准：show variables like ‘%long%’

  mysql> show variables like '%long_query_time%';
  +-----------------+----------+
  | Variable_name   | Value    |
  +-----------------+----------+
  | long_query_time | 10.00000 |
  +-----------------+----------+
  1 row in set (0.00 sec)
  
  mysql> show variables like '%slow%';
  +---------------------------+--------------------------------+
  | Variable_name             | Value                          |
  +---------------------------+--------------------------------+
  | log_slow_admin_statements | OFF                            |
  | log_slow_slave_statements | OFF                            |
  | slow_launch_time          | 2                              |
  | slow_query_log            | ON                             |
  | slow_query_log_file       | /var/lib/mysql/ubuntu-slow.log |
  +---------------------------+--------------------------------+
  5 rows in set (0.00 sec)
  

• 开启日志：set global slow_query_log = on;
• 修改时间标准：set long_query_time = 0.5;
• slow_query_log_file为日志文件所在路径；
• 查看日志
  [……]

  继续阅读