Consistent Hashing: Distributing Load Without a Full Reshuffle
Naive hashing (hash(key) % N) works fine until you add or remove a node — then N changes and almost every key maps to a different server. For a distributed cache or shard, that means a near-total cache miss storm or a mass data migration, right when you can least afford it.
Consistent hashing fixes this by mapping both nodes and keys onto the same ring, so a topology change only remaps the keys between the changed node and its neighbor.
The Ring
graph LR
