An efficient method and apparatus for storing and retrieving memory ranges is disclosed. A key range that is stored or to be stored is associated with a node in the tree hierarchy encompassing the entire memory address space. All previously stored ranges are listed or otherwise associated with each node, and all possible nodes that may contain ranges that overlap the key range, regardless of starting or ending locations or range length, are found. Partitions are developed in the tree structure of the available address space and the width of the key range (w), the widths of the partitions (d), and the range of offsets in the starting location of the key range with respect to a partition (o) are used to develop a formula that finds a partition suitable for storing the key range. Hashing and dynamic tree building may be used.