3 ms·
I’m not sure I understand the way you’re using the vocabulary. Consistency is a read operation concept not write. There is no online reads for logs. Availabili
by fnordpiglet 3y ago
I’m not sure I understand the way you’re using the vocabulary. Consistency is a read operation concept not write. There is no online reads for logs.
Availability is achieved if at least one writer acknowledges a write. In a partition, it means when you have multiple parts of the system disagreeing about the write contents due to a partition in the network. But because logs are immutable and write only, this doesn’t happen in any situation. The only situation this might occur is if you’re maintaining a distributed ratchet with in delivery order semantics rather than eventually consistent temporal semantics- in which case you will never have CAP. But that’s an insanely rare edge case.
Note CAP doesn’t ensure perfect durability. I feel like you’re confusing consistency with durability. Consistency means after I’ve durably written something all nodes agree on read it’s been written. Since logs don’t support read on the online data plane this is trivially not an issue. Any write acknowledgment is sufficient.