A Tabu-Based Cache to Improve Range Queries on Prefix Trees

Distributed Hash Tables (DHTs) provide the substrate to build large scale distributed applications over Peerto-Peer networks. A major limitation of DHTs is that they only support exact-match queries. In order to offer range queries over a DHT it is necessary to build additional indexing structures. Prefix-based indexes, such as Prefix Hash Tree (PHT), are interesting approaches for building distributed indexes on top of DHTs. Nevertheless, the lookup operation of these indexes usually generates a high amount of unnecessary traffic overhead which degrades system performance by increasing response time. In this paper, we propose a novel distributed cache system called Tabu Prefix Table Cache (TPT-C), aiming at improving the performance of the Prefix-trees. We have implemented our solution over PHT, and the results confirm that our searching approach reduces up to a 70% the search latency and traffic overhead. Keywords-Distributed Cache, Information Retrieval, Complex Queries, Peer-to-Peer, DHT.