一、背景

  由於專案的業務是不斷往前跑的，所以難免資料庫的表的量會越來越龐大，不斷的擠佔硬碟空間。即使再大的空間也支撐不起業務的增長，所以定期刪除不必要的資料是很有必要的。在我們專案中由於不清理資料，一個表佔的空間竟然達到了4G之多。想想有多可怕...

  這裡介紹的是用MySQL 建立一個定時器Event，定期清除掉之前的不必要事件。

二、內容

#1、建立儲存過程供事件呼叫
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、開啟event(要使定時起作用，MySQL的常量GlOBAL event_schduleer 必須為on 或者1)
show variables like 'event_scheduler'
set global event_scheduler='on'

#3、建立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、開啟Event 事件
alter event middle_event on completion preserve enable;

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