A Peer-to-Peer Database Server based on BitTorrent John Colquhoun Paul Watson John Colquhoun Paul Watson

2 Introduction If a database server receives queries faster than it can process them, performance becomes unacceptable Similar problems have been addressed in the domain of file-sharing by the use of Peer-to-Peer (P2P) technologies Can we utilise the combined processing power, disk space and memory of individual clients to reduce the load on the server? We examine how P2P techniques could be applied within a database environment and introduce the Wigan P2P database, derived from the BitTorrent file-sharing protocol Potential applications in e-Science and e-Commerce

3 System Architecture Advertise: SELECT * FROM t Advertise: SELECT id, value FROM t WHERE t.Id < 100 Query: SELECT id, value FROM t WHERE t.Id < 100 Advertise: SELECT id, value FROM t WHERE t.id < 100 Query: SELECT id, value FROM t WHERE t.Id < 10 Advertise: SELECT id, value FROM t WHERE t.Id < 10 Query: SELECT id, value FROM t WHERE t.id < 100 Tracker

4 Implementation A simulator of Wigan The TPC-H benchmark database was used to evaluate the design Identified cases where Wigan offered a performance advantage over a Client-Server database and those areas where it did not Experiment results – a busy system where peers submitted one of a choice of five queries, however some submitted an entirely random query over a table of 10,000 tuples

5 Simulator Results

6 Current work Live Wigan system Currently under development, using algorithms developed for the simulator Written in Java and uses OGSA-DAI Also uses the TPC-H benchmark database Experiments are ongoing; in the future the live version will be used to investigate extensions to the Wigan system

7 Live System Results (1) Initial experiments with the live system involved comparing Wigan against accessing data directly from SQLServer via JDBC One of the TPC-H tables is large (approx 6 million tuples) and hence SQLServer takes some time to evaluate queries on this table, regardless of the result set size However, in Wigan, connecting to a peer that already has the query results reduces the response time In this experiment, all peers submitted the same query

8 Live System Results (2)

9 Summary We designed, implemented & evaluated the Wigan Peer-to-Peer Database System Derived from the popular BitTorrent file-sharing protocol The first database server that uses P2P to scale over multiple peers Simulator shows Wigan can outperform client-server db when: There are enough peers available to reduce the load on the seed There is sufficient overlap between the queries The system is sufficiently busy so a traditional database server would become overloaded