A method for mapping a first address space to a second address space is provided. In some embodiments, the method includes creating a first array of lookup entries and one or more second arrays of metadata entries for maintaining an ordering among the lookup entries using a tree structure. Each of the metadata entries includes one or more data index values identifying a corresponding one of the lookup entries by its position in the first array and one or more metadata index values identifying a corresponding one of the metadata entries by its position in one of the one or more second arrays. The method further includes receiving a request including a lookup value, traversing the tree structure to locate a lookup entry corresponding to the lookup value, and when the lookup value is located among the lookup entries, using the located lookup entry to process the request.