Related: Redis 1.1 (currently in beta but ready for some test) implements a sorted type supporting range queries. It's pretty useful when the need is to take mi

Related: Redis 1.1 (currently in beta but ready for some test) implements a sorted type supporting range queries. It's pretty useful when the need is to take million of items sorted with very fast top-N items operations or items with score between min and max, especially in presence of continuous updates to the items scores. If you are interested check http://code.google.com/p/redis/wiki/CommandReference http://code.google.com/p/redis/wiki/CommandReference (All the commands prefixed with "Z" are about the Sorted Set data type). Btw both insert / remove / and update-score operations are O(Log(N)). Top-N items is O(N) since the list of items is already sorted. Redis 1.1 will be released as stable in one or two months at max. For data structures and algorithms geeks: the sorted data type of Redis is implemented with a skip list, hacked to actually build a doubly-liked list, with the backward pointers being only at level 0 (we have reverse range operations, ZREVRANGE). Every element is also taken inside an hash table, so that it's possible to update the score of an element already inside the sorted set in O(Log(N)) time because we can get the old score in O(1) from the hash table, and then find the element in the skip list. Even when the scores are not distributed but there are large clusters of elements with the same score, the update is still O(Log(N)) thanks to some interesting trick.