Consistent hashing

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In computer science, consistent hashing^[1][2] is a special kind of hashing technique such that when a hash table is resized, only ${\displaystyle n/m}$ keys need to be remapped on average where ${\displaystyle n}$ is the number of keys and ${\displaystyle m}$ is the number of slots. In contrast, in most traditional hash tables, a change in the number of array slots causes nearly all keys to be remapped because the mapping between the keys and the slots is defined by a modular operation.

Consistent hashing evenly distributes cache keys across shards, even if some of the shards crash or become unavailable.^[3]