Exploiting common subqueries for complex query optimization

  • Authors:
  • Yingying Tao;Qiang Zhu;Calisto Zuzarte

  • Affiliations:
  • Department of Computer and Information Science, The University of Michigan, Dearborn, MI;Department of Computer and Information Science, The University of Michigan, Dearborn, MI;IBM Toronto Laboratory, Markham, Ontario, Canada L6G 1C7

  • Venue:
  • CASCON '02 Proceedings of the 2002 conference of the Centre for Advanced Studies on Collaborative research
  • Year:
  • 2002

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Abstract

As database technology is applied to more and more application areas, user queries on a database become more and more complex. Existing query optimization techniques were not developed for dealing with complex queries and may suffer from some serious problem such as intolerably long optimization time and poor optimizing results. To tackle this challenge, we introduce a new technique to improve the quality of complex query optimization in this paper. The key idea is to exploit the common subqueries that often appear in a complex query and reuse the optimization work done for each common subquery. An algorithm to identify common subqueries efficiently and generate a high-quality execution plan for a given complex query is proposed. The complexity of the algorithm is analyzed. Experiments demonstrate that this proposed polynomial-time technique is quite promising in optimizing complex queries for a database management system.