Consistent hashing

Uncommon card · No. 198032

In computer science, consistent hashing is a special kind of hashing technique such that when a hash table is resized, only n / m {\displaystyle n/m} keys need to be remapped on average where n {\displaystyle n} is the number of keys and m {\displaystyle m} is the number of slots. Consistent hashing evenly distributes cache keys across shards, even if some of the shards crash or become unavailable. 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 is used by Content Delivery Networks because it is useful for distributing requests for content from a rotating population of web servers. Tim Berners-Lee credits consistent hashing algorithms, and Daniel...

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