consistent hashing

When you shard a vector index or route requests across model replicas, naive 'hash mod N' reshuffles everything when N changes. Consistent hashing moves only a small fraction. Here is the implementation.

The Dynamo question. Interviewers want three decisions made cleanly: how you partition keys so adding nodes does not reshuffle everything, how you replicate for durability, and where you land on the CAP spectrum. Here is how to reason about all three with concrete quorum math.

A cache is easy until you scale it across many nodes. Then you face consistent hashing, eviction policy, the thundering herd on a cache miss, hot keys, and how stale you can tolerate. Here is the design that holds up under real traffic.