mysql> show variables like 'slow_query%';
+---------------------+--------------------------------+
| Variable_name       | Value                          |
+---------------------+--------------------------------+
| slow_query_log      | ON                             |
| slow_query_log_file | /usr/local/mysql/data/slow.log |
+---------------------+--------------------------------+

mysql> show variables like 'long_query_time';
+-----------------+----------+
| Variable_name   | Value    |
+-----------------+----------+
| long_query_time | 1.000000 |
+-----------------+----------+

set global long_query_time=2;

set global log_output='TABLE';

mysql> show variables like '%log_output%';

执行一条慢查询 SQL 语句

mysql> select sleep(2);

查看是否生成慢查询日志

ls /usr/local/mysql/data/slow.log

查询总计多少 slow

show global status like '%Slow_queries%'