Distributed Cache and Consistent Hashing

A distributed cache is an extension of the traditional concept of cache used in a single locale.
In computer architecture a locale is an abstraction of the concept of a localized set of hardware resources which are close enough to enjoy uniform memory access. For instance, on a computer cluster each node may be considered a locale given that there is one instance of the operating system and uniform access to memory for processes running on that node.

Consistent hashing is a special kind of hashing such that when a hash table is resized, only K / n keys need to be remapped on average, where K is the number of keys, and n 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.

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