A locality-preserving cache-oblivious dynamic dictionary

Abstract

This paper presents a simple dictionary structure designed for a hierarchical memory. The proposed data structure is cache-oblivious and locality-preserving. A cache-oblivious data structure has memory performance optimized for all levels of the memory hierarchy even though it has no memory-hierarchy-specific parameterization. A locality-preserving dictionary maintains elements of similar key values stored close together for fast access to ranges of data with consecutive keys. The data structure presented here is a simplification of the cache-oblivious B-tree of Bender, Demaine, and Farach-Colton. The structure supports search operations on N data items using O(log B N+1) block transfers at a level of the memory hierarchy with block size B. Insertion and deletion operations use O(log B N+log 2 N/ B+1) amortized block transfers. Finally, the data structure returns all k data items in a given search range using O(log B N+ k/ B+1) block transfers. This data structure was implemented and its performance was evaluated on a simulated memory hierarchy. This paper presents the results of this simulation for various combinations of block and memory sizes.