Finding Equivalent Rewritings in the Presence of Arithmetic Comparisons

  • Foto Afrati
  • Rada Chirkova
  • Manolis Gergatsoulis
  • Vassia Pavlaki
Part of the Lecture Notes in Computer Science book series (LNCS, volume 3896)

Abstract

The problem of rewriting queries using views has received significant attention because of its applications in a wide variety of data-management problems. For select-project-join SQL (a.k.a. conjunctive) queries and views, there are efficient algorithms in the literature, which find equivalent and maximally contained rewritings. In the presence of arithmetic comparisons (ACs) the problem becomes more complex. We do not know how to find maximally contained rewritings in the general case. There are algorithms which find maximally contained rewritings only for special cases such as when ACs are restricted to be semi-interval. However, we know that the problem of finding an equivalent rewriting (if there exists one) in the presence of ACs is decidable, yet still doubly exponential. This complexity calls for an efficient algorithm which will perform better on average than the complete enumeration algorithm. In this work we present such an algorithm which is sound and complete. Its efficiency lies in that it considers fewer candidate rewritings because it includes a preliminary test to decide for each view whether it is potentially useful in some rewriting.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Foto Afrati
    • 1
  • Rada Chirkova
    • 2
  • Manolis Gergatsoulis
    • 3
  • Vassia Pavlaki
    • 1
  1. 1.Department of Electrical and Computing EngineeringNational Technical University of Athens (NTUA)AthensGreece
  2. 2.Computer Science DepartmentNorth Carolina State UniversityRaleigh
  3. 3.Department of Archive and Library SciencesIonian UniversityCorfuGreece

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