[Cassandra] Safer consistency settings #9171
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ReubenBond
approved these changes
Oct 15, 2024
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While the EACH_QUORUM/LOCAL_QUORUM is correct for consistency and does provider a faster read, it also will make it impossible to write if a single data center is unreachable.
For example, a Cassandra cluster across three data centers would need to be able to have each individual data center achieve it's own quorum for the write to be successful.
With using QUORUM/QUORUM for write/read, there only needs to be a single quorum across the whole cluster. If an entire data center in the three DC scenario is unreachable, then you can still have a Quorum from nodes in the reachable two data centers to complete a write.
The EACH_QUORUM for writes seems like it's more dangerous than the equally consistent QUORUM/QUORUM settings.
Microsoft Reviewers: Open in CodeFlow