参考文档:https://blog.csdn.net/leshami/article/details/39829605
参考文档:https://www.cnblogs.com/deverz/p/11066043.html

开启慢查询日志

检查是否开启慢查询日志
mysql> show variables like 'slow_query_log'; 
+----------------+-------+
| Variable_name  | Value |
+----------------+-------+
| slow_query_log | OFF   |
+----------------+-------+
1 row in set

开启慢查询日志
mysql> set global slow_query_log = 1;

再次检查是否开启慢查询日志
mysql> show variables like 'slow_query_log';
+----------------+-------+
| Variable_name  | Value |
+----------------+-------+
| slow_query_log | ON    |
+----------------+-------+

设置日志文件的路径
set global slow_query_log_file = '/var/lib/mysql/dajx-dev-slow.log';

检查慢查询的阀值
show variables like '%long_query_time%';
+-----------------+-----------+
| Variable_name   | Value     |
+-----------------+-----------+
| long_query_time | 10.000000 |
+-----------------+-----------+
1 row in set (0.001 sec)

修改慢查询的阀值为自己觉得合适的值
set global long_query_time = 1;

这样执行时间大于1秒的sql就都会记录在/var/lib/mysql/dajx-dev-slow.log文件中了