MySQL数据库 Event 定时执行任务.

一、背景

由于项目的业务是不断往前跑的，所以难免数据库的表的量会越来越庞大，不断的挤占硬盘空间。即使再大的空间也支撑不起业务的增长，所以定期删除不必要的数据是很有必要的。在我们项目中由于不清理数据，一个表占的空间竟然达到了4G之多。想想有多可怕...

这里介绍的是用MySQL 建立一个定时器Event，定期清除掉之前的不必要事件。

二、内容

#1、建立存储过程供事件调用
delimiter//
drop procedure if exists middle_proce//
create procedure middle_proce()
begin
DELETE FROM jg_bj_comit_log WHERE comit_time < SUBDATE(NOW(),INTERVAL 2 MONTH);
optimize table jg_bj_comit_log;
DELETE FROM jg_bj_order_create WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH);
optimize table jg_bj_order_create;
DELETE FROM jg_bj_order_match WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH);
optimize table jg_bj_order_match;
DELETE FROM jg_bj_order_cancel WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH);
optimize table jg_bj_order_cancel;
DELETE FROM jg_bj_operate_arrive WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH);
optimize table jg_bj_operate_arrive;
DELETE FROM jg_bj_operate_depart WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH);
optimize table jg_bj_operate_depart;
DELETE FROM jg_bj_operate_login WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH);
optimize table jg_bj_operate_login;
DELETE FROM jg_bj_operate_logout WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH);
optimize table jg_bj_operate_logout;
DELETE FROM jg_bj_operate_pay WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH);
optimize table jg_bj_operate_pay;
DELETE FROM jg_bj_position_driver WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH);
optimize table jg_bj_position_driver;
DELETE FROM jg_bj_position_vehicle WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH);
optimize table jg_bj_position_vehicle;
DELETE FROM jg_bj_rated_passenger WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH);
optimize table jg_bj_rated_passenger;
end//
delimiter;

#2、开启event(要使定时起作用，MySQL的常量GlOBAL event_schduleer 必须为on 或者1)
show variables like 'event_scheduler'
set global event_scheduler='on'

#3、创建Evnet事件
drop event if exists middle_event;
create event middle_event
on schedule every 1 DAY STARTS '2017-12-05 00:00:01'
on completion preserve ENABLE
do call middle_proce();

#4、开启Event 事件
alter event middle_event on completion preserve enable;

#5、关闭Event 事件
alter event middle_event on completion preserve disable;