Case study: Scoop for partial read from P2P database

In this paper we propose Scoop, a mechanism to implement the “partial read operation” for peer-to-peer databases. A peer-to-peer database is a database that its relations are horizontally fragmented and distributed among the nodes of a peer-to-peer network. The partial read operation is a data retrieval operation required for approximate query processing in peer-to-peer databases. A partial read operation answers to β -queries: given β ∈ [0,1] and a relation R, a fraction β of the tuples in R must be retrieved from the database to answer a β -query. Despite the simplicity of the β -query, due to the distributed, evolving and autonomous nature of the peer-to-peer databases correct and efficient implementation of the partial read operation is challenging. Scoop is designed based on an epidemic dissemination algorithm. We model the epidemic dissemination as a percolation problem and by rigorous percolation analysis tune Scoop per-query and on-the-fly to answer β queries correctly and efficiently. We prove the correctness of Scoop by theoretical analysis, and verify the efficiency of Scoop in terms of query cost and query time via extensive simulation. Farnoush Banaei-Kashani University of Southern California, Department of Computer Science, Los Angeles, CA 900890781 e-mail: [email protected] Cyrus Shahabi University of Southern California, Department of Computer Science, Los Angeles, CA 900890781 e-mail: [email protected]