An O(N2) equivalence algorithm for fan-out free queries

  • Pratul Dublish
  • S. N. Maheshwari
Complexity And Optimization
Part of the Lecture Notes in Computer Science book series (LNCS, volume 326)


An equivalence algorithm for fan-out free queries, which form an untyped subclass of conjunctive queries, based on an extension of the implication graph technique is presented. This algorithm runs in O(n2) time where n is the size of the queries involved. This algorithm subsumes all known equivalence testing algorithms for various subclasses of fan-out free queries.


Symbol Mapping Horn Clause Graph Isomorphism Conjunctive Query Pruning Process 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. [AHU]
    A.V.Aho, J.E.Hopcroft and J.D. Ullman, The Design and Analysis of Computer Algorithms, Addison-Wesley.Google Scholar
  2. [ASU]
    A.V.Aho, Y.Sagiv and J.D.Ullman, Equivalences Among Relational Expressions, SIAM Journal on Computing, Vol 8, No 2, May 1979.Google Scholar
  3. [CH]
    A.K.Chandra and D.Harel, Horn Clause Programs and Generalizations, Journal of Logic Programming, Vol 2, 1985.Google Scholar
  4. [CM]
    A.K.Chandra and P.M.Merlin, Optimal Implementation of Conjunctive Queries in Relational Databases, Proc. of 9th ACM-STOC, May 1977.Google Scholar
  5. [DM]
    P.Dublish and S.N.Maheshwari, An O(n2) Algorithm for Fan-out Free Query Optimization, Proc. of FST&TCS 7, Lecture Notes in Computer Science, Vol 287, Springer-Verlag.Google Scholar
  6. [JK]
    D.S.Johnson and A.Klug,Optimizing Conjunctive Queries that contain Untyped Variables, SIAM Journal on Computing, Vol. 12, No. 4, Nov 1983.Google Scholar
  7. [MDM]
    B.N.S.Murthy, P.Dublish and S.N.Maheshwari, Some Negative Results on the Optimization of Conjunctive Queries, Technical Report TR 85/01, Deptt. of Computer Science and Engg., IIT Delhi, Dec 1985.Google Scholar
  8. [Mai]
    D.Maier, The Theory of Relational Database, Computer Science Press, 1983.Google Scholar
  9. [Sag]
    Y.Sagiv, Quadratic Algorithms for Minimizing Joins in Restricted Relational Expressions, SIAM Journal on Computing, Vol. 12, No. 2, May 1983.Google Scholar
  10. [SY]
    Y.Sagiv and M.Yannakakis, Equivalences Among Relational Expressions with Union and Difference Operators, Journal of ACM, Vol 27, No. 4, Oct 1980.Google Scholar
  11. [Ull]
    J.D.Ullman, Principles of Database Systems, Computer Science Press, 1982.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1988

Authors and Affiliations

  • Pratul Dublish
    • 1
  • S. N. Maheshwari
    • 1
  1. 1.Department of Computer Science & EngineeringIndian Institute of TechnologyDelhi New DelhiIndia

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