[erlang-questions] finding the nearest key in a key-value table

[Joe Armstrong]

What's the best data structure to support a "nearest key" operation?

I want a data structure that supports the following operations:

     new() -> NewTree

     insert(Key, Value, Tree) -> NewTree

    delete(Key, Tree)  -> NewTree

    nearest(Key, N, Tree)     -> [{Key1,Val1},{Key2,Val2} ...].

    Keys are 20 byte binaries, values are 6 byte binaries

    The maximum number of keys of Key-Value pairs is 10 million.

   nearest(Key, N, Tree) returns the N nearest items to Key in the tree

   "near" means that the keys are near to each other. Often the key I want
will not
be in the tree, so I want nearby keys. The nearness measure is just the
"distance" between the two keys (ie the nearest N keys to the given key if
the keys were to
be sorted)

Are there any Erlang libraries that do this?

/Joe
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