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Mysql RELICATION对存过的处理是怎样的

2025-06-22 17:04来源:互联网 [ ]

昨天鹰眼需求从一个大表(27G)删除47026788数据;
用存储过程通过主键删除实现;用了1个小时50分钟;
QPS=47026788/(60*110)=7125.2709
这个速度已经满快了,都是随机读;[@more@]


当时我在想,MASTER用近两个小时,是不是SLAVE也用这么长时间么;

到SLAVE一看,根本没有SQL在跑;
而且表里数据已经被清空;

通过测试,我们发现MASTER在应用存过时,在BINLOG里记录的是真正最后执行的DML操作;
比如:
#101202 13:58:43 server id 2 end_log_pos 15842 Querythread_id=4058 exec_time=0 error_code=0
SET TIMESTAMP=1291269523/*!*/;
delete from test where id = NAME_CONST('v_entry_id',238)
/*!*/;
# at 15842
#101202 13:58:43 server id 2 end_log_pos 15974 Querythread_id=4058 exec_time=0 error_code=0
SET TIMESTAMP=1291269523/*!*/;
delete from test where id = NAME_CONST('v_entry_id',240)
/*!*/;
# at 15974
#101202 13:58:43 server id 2 end_log_pos 16106 Querythread_id=4058 exec_time=0 error_code=0
SET TIMESTAMP=1291269523/*!*/;
delete from test where id = NAME_CONST('v_entry_id',242)
/*!*/;

...

所以只要MASTER执行完后,就会马上应用到SLAVE;


下面是一个删除数据的存储过程范例:
================================================
use test;
drop procedure if exists delete_expired;
delimiter //
CREATE PROCEDURE delete_expired(in in_date date)
BEGIN
declare done int default 0;
declare rowcnt int default 0 ;
declare v_entry_id int;
declare cur_del cursor For select id from test ;
DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1;
open cur_del;
start transaction;
cursor_loop:loop
fetch cur_del into v_entry_id;
if done=1 then leave cursor_loop ;
end if ;
delete from test where id =v_entry_id;
set rowcnt=rowcnt+1;
if rowcnt=1000 then
set rowcnt =0 ;
commit;
start transaction;
end if ;
end loop cursor_loop ;
commit ;
close cur_del;
END ;//
DELIMITER ;

call delete_expired ('2010-01-10');
drop procedure if exists delete_expired ;
===========================================================