MYSQL慢查询和日志实例讲解

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

mysql> show variables like 'long_query_time';
+-----------------+-----------+
| Variable_name | Value  |
+-----------------+-----------+
| long_query_time | 10.000000 |
+-----------------+-----------+

mysql> set global slow_query_log='ON';

mysql> set global slow_query_log_file='/usr/local/mysql/data/slow.log';

mysql> set global long_query_time=1;

[mysqld] slow_query_log = ON slow_query_log_file = /usr/local/mysql/data/slow.log long_query_time = 1

service mysqld restart

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 |
+-----------------+----------+

mysql> select sleep(2);

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