I did not even know this was a thing (without using some less well-known mysql extension like Galera), but just googled and found a brief document from Digital Ocean on exactly how to do this with stock MySQL. And here it is, right in the fine manual, supported since 5.1.18.
I don't know how to ask this more precisely, but how are races and concurrent writes on both masters handled? Is it still "ACID safe" writing across the cluster, or would you use something like this as a hot-spare for promotion in case of failover only?
Yeah. I thought about it, and there is so much work on things like etcd and zookeeper, I would have already heard about it if multi-master MySQL was really a thing worth writing home about. But still, cool to find out they're advertising it.
I don't know how to ask this more precisely, but how are races and concurrent writes on both masters handled? Is it still "ACID safe" writing across the cluster, or would you use something like this as a hot-spare for promotion in case of failover only?