mysql定时清理任务

随着时间的推移，数据库中积压的数据越来越多，数据文件越来越大，查询越来越慢。在历史数据不重要的情况下，我们可以对数据表中的过期数据进行清理。让数据库运行在一个平稳的环境中,主要方法是通过定时事件，触发清理任务。

1. 查看是否开启了事件功能

mysql> show variables like '%event_sc%';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| event_scheduler | OFF   |
+-----------------+-------+
1 row in set (0.00 sec)

如上所示，事件调度器是处于关闭状态的。
2. 打开事件功能
2.1 临时打开,但下次重启mysql就失效了。
在这里SET GLOBAL event_scheduler = 1; 和 SET GLOBAL event_scheduler = ON; 效果是一样的

mysql> SET GLOBAL event_scheduler = ON;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like '%event_sc%';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| event_scheduler | ON    |
+-----------------+-------+
1 row in set (0.00 sec)

2.2 修改my.cnf, 添加配置，永久打开

[root@localhost data]# vim /etc/my.cnf 

[mysqld]
event_scheduler=ON

然后登录mysql，如2.1，执行SET GLOBAL event_scheduler = ON;

3. 创建事件
   只保留DATA_FILE中最近九十天的数据

-- 自动删除过期数据
drop PROCEDURE  if exists autodel;
DELIMITER // 
CREATE PROCEDURE autodel()
    BEGIN
        delete from DATA_FILE where DATE(RECEIVE_TIME) <= DATE(DATE_SUB(NOW(),INTERVAL 90 day));
    END //
DELIMITER ;

-- 定时清理事件
drop EVENT  if exists event_auto_del_data;
CREATE EVENT `event_auto_del_data`   
ON SCHEDULE EVERY 90 DAY STARTS  now() 
ON COMPLETION NOT PRESERVE ENABLE DO CALL autodel(); 

4. 显示事件show events;

mysql> show events;
+---------+---------------------+---------+-----------+-----------+------------+----------------+----------------+---------------------+------+---------+------------+----------------------+----------------------+--------------------+
| Db      | Name                | Definer | Time zone | Type      | Execute at | Interval value | Interval field | Starts              | Ends | Status  | Originator | character_set_client | collation_connection | Database Collation |
+---------+---------------------+---------+-----------+-----------+------------+----------------+----------------+---------------------+------+---------+------------+----------------------+----------------------+--------------------+
| XXDB | event_auto_del_data | root@%  | SYSTEM    | RECURRING | NULL       | 90             | DAY            | 2021-01-22 14:57:14 | NULL | ENABLED |          0 | utf8                 | utf8_general_ci      | utf8_general_ci    |
+---------+---------------------+---------+-----------+-----------+------------+----------------+----------------+---------------------+------+---------+------------+----------------------+----------------------+--------------------+
1 row in set (0.00 sec)

5. 开启关闭事件

ALTER EVENT event_auto_del_data  ON COMPLETION PRESERVE ENABLE; //开启某事件
ALTER EVENT event_auto_del_data  ON COMPLETION PRESERVE DISABLE; //关闭某事件

6. 执行存储过程

call autodel;