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I'm always curious when people ask about "multi-master" what exsctly they mean and with which tradeoffs. What use case do you envision?
by redwood 10y ago
I'm always curious when people ask about "multi-master" what exsctly they mean and with which tradeoffs. What use case do you envision?
- user5994461 10y agoIt means you can write to any node.
- spacemanmatt 10y agoThat is what people think they want when they do not understand the tradeoffs involved, typically.
- bsg75 10y agoMulti-master works wonderfully until it does not. Then you have a terrible mess of inconsistent data.
- user5994461 10y agoThere can't be high availability if there is only ever one node that accepts writes. There can't be sharding if there is only ever one node that performs writes.
- redwood 10y agoI'm genuinely curious what you mean here when you say high availability? Do you mean that during a distributed consensus failover timeframe, it is unacceptable for writes to be queued at the client?
- user5994461 10y agoIt means that the system is still available when one node is dead.
- redwood 10y agoWhen you say that there can't be sharding without more than one one node taking writes, I totally see where you're coming from. And I agree with you. Typically that means that there is a logical isolation between which data goes to which shard so this avoids conflicts too. Usually when people talk about "multimaster" I do not believe they're thinking of this particular scenario but I may be wrong. I'm not familiar but does postgres not shard?
- user5994461 10y agoThere are two cases of multi-master. - All nodes have all data (no sharding). - No nodes have all data (sharding).
- redwood 10y agoOkay, but in your use case, what should happen when two nodes get conflicting writes at approximately the same time?
- user5994461 10y agoDepends on the system. Read the documentation.
- redwood 10y agoWell since you were asking about this topic, I guess what I was trying to get at is what is it that you particularly were hoping to see from the community?