mysql命令行怎么开启慢查询日志

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：

（推荐教程：mysql教程）

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)

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