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Return to Papers In this paper, we present novel techniques for performing query optimization in databases, such as multimedia and web databases, which rely on top-k predicates. We propose an optimization model that (1) takes into account different binding patterns associated with query predicates and (2) considers the variations in the query result size (or coverage), depending on the execution order. We address the additional complexity and the well-known NP-complete nature of the query optimization problem by adaptively reducing the granularity of the search space. For this purpose, unlike the data histograms which capture the data distribution, we propose opt-histograms that capture the distribution of sub-query-plan values over many query optimization tasks. ![]() DiSC'02 © 2003 Association for Computing Machinery |