Consistent hashing is a scheme that provides hash table functionality
in a way that the addition or removal of one slot does not
significantly change the mapping of keys to slots. In contrast, in
most traditional hash tables, a change in the number of array slots
causes nearly all keys to be remapped.

Consistent hashing was introduced in 1997 as a way of distributing
requests among a changing population of web servers. More recently, it
and similar techniques have been employed in distributed hash tables.

WWW:	http://search.cpan.org/dist/Set-ConsistentHash/