mysql開啟關閉慢查詢日志

在日常開發中，為了監控數據庫的執行情況，往往我們需要開啟慢查詢日志。通過檢查慢查詢日志來確定sql的方向。但是長時間的運行勢必導致慢查詢日志過大，這種情況就需要將舊的慢查詢日志保存起來，然后重新生成一份慢查詢日志。
————參考博客：正確安全清空在線慢查詢日志slow log的流程

查看當前慢查詢的信息

mysql> show variables like '%slow%';
+---------------------+------------------------------------------+
| Variable_name       | Value                                    |
+---------------------+------------------------------------------+
| log_slow_queries    | ON                                       |
| slow_launch_time    | 2                                        |
| slow_query_log      | ON                                       |
| slow_query_log_file | /mysqllog/slow_log/slow_queries_3306.log |
+---------------------+------------------------------------------+
4 rows in set (0.00 sec)

停止當前慢查詢日志

mysql> set global slow_query_log=0;
Query OK, 0 rows affected (0.27 sec)

mysql> show variables like '%slow%';
+---------------------+------------------------------------------+
| Variable_name       | Value                                    |
+---------------------+------------------------------------------+
| log_slow_queries    | OFF                                      |
| slow_launch_time    | 2                                        |
| slow_query_log      | OFF                                      |
| slow_query_log_file | /mysqllog/slow_log/slow_queries_3306.log |
+---------------------+------------------------------------------+
4 rows in set (0.00 sec)

重命名舊的慢查詢日志

mv slow.log slow.log.01

或者重新設置一個慢查詢日志路徑

mysql> set global slow_query_log_file='/mysqllog/slow_log/slow_queries_3306_new.log';
Query OK, 0 rows affected (0.03 sec)

開啟慢查詢日志功能

mysql> set global slow_query_log=1;
Query OK, 0 rows affected (0.01 sec)

mysql> show variables like '%slow%';
+---------------------+----------------------------------------------+
| Variable_name       | Value                                        |
+---------------------+----------------------------------------------+
| log_slow_queries    | ON                                           |
| slow_launch_time    | 2                                            |
| slow_query_log      | ON                                           |
| slow_query_log_file | /mysqllog/slow_log/slow_queries_3306_new.log |
+---------------------+----------------------------------------------+
4 rows in set (0.00 sec)