This means it is highly available and eventually consistent, but with additional consistency guarantees. Anna is strongly eventually consistent. Meaning that,

This means it is highly available and eventually consistent, but with additional consistency guarantees. Anna is strongly eventually consistent. Meaning that, regardless of the order or number of times operations are replayed, the answer will always converge to the same value given time. For example, imagine you have a default value of "False", and a convergent value of "True". You may observe "False" after the value has been set to True, but you will never observe True and then have to worry about it flipping back to False. Another example might be an integer that only grows. You can write to that integer: 1, 2, 3, 4 In any order, in parallel, or 100x each. But eventually the value will be 4 - not 1, 2, or 3. It may be 1, 2, or 3 at any time before it is 4, but the system will eventually converge to 4. This can be very useful. Let's say you have a query "X < 3". This query happens after a write of 4, but you observe 3. You know that, given that the value only ever grows, X could be 3 or higher, but it definitely isn't less than 3. So you can answer that query with the stale read. In an eventually consistent system without strong eventual consistency, after 4 gets written another write may get replayed after and make it go back to 2. This has some obvious benefits. You can cache values forever, without invalidation logic. If I had read '3' from a cache I could answer the query directly. If the read had returned '2' I would have to go fetch the latest value to know if it had grown since then. You may be asking "but what if I need to know the value right then". The answer is that you can put a strongly consistent store behind your strongly eventually consistent store. This is what is proposed in the CURP paper that I can't find this very moment. nvm got it https://www.usenix.org/conference/nsdi19/presentation/park https://www.usenix.org/conference/nsdi19/presentation/park