mysql命令行开启慢查询日志的方法：执行【set global slow_query_log='ON';】语句即可开启。通过执行【show variables like "%slow%";】语句可以检查慢查询日志是否已开启。

具体方法：

查看一下默认慢查询的时间10秒

mysql> show variables like "%long%"; +-----------------+-----------+| Variable_name | Value |+-----------------+-----------+| long_query_time | 10.000000 |+-----------------+-----------+1 row in set (0.00 sec)

设置成3秒，加上global,退出再次进入生效

mysql> set global long_query_time=3; Query OK, 0 rows affected (0.00 sec)

查看一下慢查询是不是已经开启

mysql> show variables like "%slow%"; +---------------------+---------------------------------+| Variable_name | Value |+---------------------+---------------------------------+| log_slow_queries| OFF || slow_launch_time| 2 || slow_query_log| OFF || slow_query_log_file | /usr/local/mysql/mysql-slow.log |+---------------------+---------------------------------+4 rows in set (0.00 sec)

启用慢查询

mysql> set global slow_query_log='ON';Query OK, 0 rows affected (0.28 sec)

查看是否已经开启

mysql> show variables like "%slow%"; +---------------------+---------------------------------+| Variable_name | Value |+---------------------+---------------------------------+| log_slow_queries| ON|| slow_launch_time| 2 || slow_query_log| ON|| slow_query_log_file | /usr/local/mysql/mysql-slow.log |+---------------------+---------------------------------+4 rows in set (0.00 sec)