Query Merging: Improving Query Subscription Processing in a Multicast Environment

  • Authors:
  • Arturo Crespo;Orkut Buyukkokten;Hector Garcia-Molina

  • Affiliations:
  • -;-;-

  • Venue:
  • IEEE Transactions on Knowledge and Data Engineering
  • Year:
  • 2003

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Abstract

This paper introduces techniques for reducing data dissemination costs of query subscriptions in a multicast environment. The reduction is achieved by merging queries with overlapping, but not necessarily equal, answers. The paper formalizes the query-merging problem and introduces a general framework and cost model for evaluating merging. We prove that the problem is NP-hard and propose exhaustive algorithms and three heuristic algorithms: The Pair Merging Algorithm, the Directed Search Algorithm, and the Clustering Algorithm. We develop a simulator, which uses geographical queries as a representative example for evaluating the different heuristics and show that the performance of our heuristics is close to optimal.