DPTree: A Balanced Tree Based Indexing Framework for Peer-to-Peer Systems

Peer-to-peer (P2P) systems have been widely used for exchange of voluminous information and resources among thousands or even millions of users. Since shared data are normally identified by multiple attributes, a fundamental issue in P2P systems is to efficiently support complex queries on multidimensional data. Prior works suffer from some fundamental limitations, such as being constrained to support certain types of queries, excessive maintenance overheads, and etc. In this study, we propose a framework, called distributed peer tree (DPTree), which efficiently supports various types of queries on multidimensional data in P2P systems based on balanced tree indexes. DPTree achieves the efficiency through the following designs: 1) distributing the tree structure among peers in a way preserving the nice properties of balanced tree structures yet avoiding single points of failure and performance bottlenecks; 2) organizing peers into an overlay structure that enables efficient navigation yet is easy to maintain; 3) an efficient navigation algorithm; 4) an innovative wavelet-based load balancing mechanism. Through extensive performance evaluation, we verify the superiority of DPTree over existing works.