When should you NOT use consistent hashing?
If your cluster size is truly fixed and never grows, or if rebalancing is cheap, consistent hashing adds complexity for little gain. It shines only when you scale up/down frequently (Cassandra, DynamoDB, Redis Cluster) or can't afford cache wipes (Discord's chat cache, ride-hailing surge boundaries). For a fixed 3-node Postgres replica set, stick with traditional hash mod N.
Answered in
When 87% of Your Cache VanishesConsistent hashing maps nodes and keys to a circle, so adding a server moves only 1/N of keys instead of almost all of them.
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