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andras_gerlits | 1 year ago
CAP is a bad model for more reasons than the ones listed in that article. My favourite one is that it requires Linearizability, which nobody does in SQL. The disconnect when saying "SQL is not consistent" to me is just too much. CAP is based on a badly defined idea that comes from a presentation that was wrong in what it said.
That you need to tolerate outages of entire regions is a good argument to make in itself, there's no need to point at CAP. My answer to that is that as there's a way to define consistency in a way that allows for it to manage partition problems more gracefully, and that is the model we show. If you require communication to establish consistency and stream the changes associated with the specific timeslot at the same time, partition means that the global state will move on without the changes from the partitioned areas and that they will show up once the region rejoins the global network. While separated, they can still do (SQL-) consistent reads and writes for (intra-region) records they can modify.
tsimionescu|1 year ago
In contrast, any distributed system has this property (or it may refuse the query entirely) in the face of partitions.