On Sat, Oct 9, 2021 at 11:23 PM Blake Eggleston <beggles...@apple.com.invalid> wrote:
> 1. Is it worth giving up local latencies to get full global consistency? > Most LWT use cases use > LOCAL_SERIAL. > > This isn’t a tradeoff that needs to be made. There’s nothing about Accord > that prevents performing consensus in one DC and replicating the writes to > others. That’s not in scope for the initial work, but there’s no reason it > couldn’t be handled as a follow on if needed. I agree with Jeff that > LOCAL_SERIAL and LWTs are not usually done with a full understanding of the > implications, but there are some valid use cases. For instance, you can > enable an OLAP service to operate against another DC without impacting the > primary, assuming the service can tolerate inconsistency for data written > since the last repair, and there are some others. > Come on Blake, you have all been developing software long enough to know that "there's nothing about Accord that prevents this" is close to meaningless. If it's so easy to address an overwhelmingly popular use case, then let's add it to the initial work. 2. Is it worth giving up the possibility of SQL support, to get the > benefits of deterministic transaction design? > > This is a false dilemma. Today, we’re proposing a deterministic > transaction design that addresses some very common user pain points. SQL > addresses different user pain point. If someone wants to add an sql > implementation in the future they can a) build it on top of accord b) > extend or improve accord or c) implement a separate system. The right > choice will depend on their goals, but accord won’t prevent work on it, the > same way the original lwt design isn’t preventing work on multi-partition > transactions. In the worst case, if the goals of a hypothetical sql project > are different enough to make them incompatible with accord, I don’t see any > reason why we couldn’t have 2 separate consensus systems, so long as people > are willing to maintain them and the use cases and available technologies > justify it. > I think this is the crux of our disagreement, I very much want to avoid a future where we have to maintain two separate consensus systems.
