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There is a theorem called CALM[1] (Consistency as Logical Monotonicity) that shows that systems are eventually consistent iff they are monotonic. I find that r
by j-pb 3y ago
There is a theorem called CALM[1] (Consistency as Logical Monotonicity) that shows that systems are eventually consistent iff they are monotonic.
I find that reasoning about consistency is much easier from that perspective, for example it immediately gives you an intuition on why individual CRDTs work.
1: https://arxiv.org/abs/1901.01930 https://arxiv.org/abs/1901.01930
- klabb3 3y agoSounds interesting. Is there an intuitive definition of monotonicity for the purposes of distributed systems? I mean, I thought I knew what it means, but I’m not too sure now.
- j-pb 3y agoYou never take something back. A grow set for example only ever grows. A monotonic counter only ever grows. Even a set where you can insert and delete once is like a set of counters that only ever grow (nothing: 0, added:1, removed:2). Forgetting for example is fine, but deletion is not.