Evaluating Reachability Queries over Path Collections P. Bouros 1, S. Skiadopoulos 2, T. Dalamagas 3, D. Sacharidis 3, T. Sellis 1,3 1 National Technical.

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Evaluating Reachability Queries over Path Collections P. Bouros 1, S. Skiadopoulos 2, T. Dalamagas 3, D. Sacharidis 3, T. Sellis 1,3 1 National Technical University of Athens 2 University of Peleponnese 3 Institute for Management of Information Systems – R.C. Athena SSDBM'09

Motivating example SSDBM'09

Problem definition Large path collections Frequent updates – New paths Evaluating reachability queries 1.Is there a path from node F to C? 2.Find a path from node F to C p1p1 (A, B,C,D,J) p2p2 (A, F, D, N, B,T) p3p3 (N, L, M) p4p4 (D, N, B, F, K) p5p5 (A, F, K) SSDBM'09 Path collection

Solving the problem Using a graph – Merge paths to build underlying graph – Apply graph search algorithm for queries Our approach – Algorithm pfs Visit nodes in paths in depth-first way Push to dfs stack set of nodes at once – Index path collections, P-Index, pfsP – Index path connections, H-graph & H-Index, pfsH SSDBM'09

Thank you! SSDBM'09