MySQL master-master replication and autoincrement indexes setup /etc/my.cnf

MySQL master-master replication and autoincrement indexes

If you are using master-slave replication, than most likely you will design your application the way to write to master and read from slave or several slaves. But when you are using master-master replication you are going to read and write to any of master servers. So, in this case the problem with autoincremental indexes will raise. When both servers will have to add a record (different one each server simultaneously) to the same table. Each one will assign them the same index and will try to replicate to the salve, this will create a collision. Simple trick will allow to avoid such collisions on MySQL server.
On the Master 1/Slave 2 add to /etc/my.cnf:

auto_increment_increment= 2

auto_increment_offset   = 1

On the Master 2/Slave 1 add to /etc/my.cnf:

auto_increment_increment= 2

auto_increment_offset   = 2