Parallel processing of graph reachability in databases

In this paper we consider parallel processing of a graph represented by a database relation, and we achieved two objectives. First, we propose a methodology for analyzing the speedup of a parallel processing strategy with the purpose of selecting at runtime one of several candidate strategies, depending on the hardware architecture and the input graph. Second, we study the single-source reachability problem, namely the problem of computing the set of nodes reachable from a given node in a directed graph. We propose several parallel strategies for solving this problem, and we analyze their performance using our new methodology. The analysis is confirmed experimentally in a UNIX-Ethernet environment. We also extend the results to the transitive closure problem.A preliminary shortened version of this paper has appeared inPDIS. See Ref. 1.This author's work was supported in part by NSF Grant 90-03341.This author's work was supported in part by the Natural Sciences and Engineering Research Council of Canada.This author's work was supported in part by NSF Grant 90-03341.