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Mysql双主自增长冲突处理_MySQL

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Jun 01, 2016 pm 01:31 PM

data sheetserver

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Mysql双主自增长冲突处理

多主互备和主从复制有一些区别，因为多主中都可以对服务器有写权限，所以设计到自增长重复问题

出现的问题（多主自增长ID重复）

1:首先我们通过A,B的test表结构

2:掉A，在B上对数据表test(存在自增长ID)执行插入操作，返回插入ID为1

3:后停掉B，在A上对数据表test(存在自增长ID)执行插入操作，返回的插入ID也是1

4:然后我们同时启动A,B，就会出现主键ID重复

解决方法：

我们只要保证两台服务器上插入的自增长数据不同就可以了

如：A查奇数ID，B插偶数ID，当然如果服务器多的话，你可以定义算法，只要不同就可以了

在这里我们在A,B上加入参数，以实现奇偶插入

A：my.cnf上加入参数

auto_increment_offset = 1

auto_increment_increment = 2

这样A的auto_increment字段产生的数值是：1, 3, 5, 7, …等奇数ID了

B：my.cnf上加入参数

auto_increment_offset = 2

auto_increment_increment = 2

这样B的auto_increment字段产生的数值是：2, 4, 6, 8, …等偶数ID了

可以看出，你的auto_increment字段在不同的服务器之间绝对不会重复，所以Master-Master结构就没有任何问题了。当然，你还可以使用3台，4台，或者N台服务器，只要保证auto_increment_increment = N 再设置一下auto_increment_offset为适当的初始值就可以了，那样，我们的MySQL可以同时有几十台主服务器，而不会出现自增长ID 重复。

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