Updating logical databases containing null values

  • Marianne Winslett
Contributed Papers
Part of the Lecture Notes in Computer Science book series (LNCS, volume 243)

Abstract

We show that it is natural to extend the concept of database updates to encompass databases with incomplete information in the form of null values, or tuple attribute values that are known to exist but whose exact value is not known. Our approach embeds the incomplete database and the updates in the language of mathematical logic, which we believe has strong advantages over relational tables and traditional data manipulation languages in the incomplete information situation. We present semantics for our update operators, and provide an algorithm to perform the operations. The computational complexity of the algorithm is examined, and a lazy evaluation scheme coupled with simple user-supplied cost limits is recommended to avoid undesirable expense during execution. This paper extends results presented in [Winslett 86a].

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7. References

  1. [Abiteboul 85]
    S. Abiteboul, G. Grahne, “Update Semantics for Incomplete Databases,” Proc. VLDB Conf., Stockholm, August 1985.Google Scholar
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    R. Fagin, J. D. Ullman, and M. Y. Vardi, “On the Semantics of Updates in Databases,” Proc. of the 2nd ACM PODS, April 1983.Google Scholar
  3. [Fagin 84]
    R. Fagin, G. M. Kuper, J. D. Ullman, and M. Y. Vardi, “Updating Logical Databases,” Proc. of the 3rd ACM PODS, April 1984; reprinted in Advances in Computing Research 3, JAI Press, 1986.Google Scholar
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    T. Imielinski and W. Lipski, “Incomplete Information in Relational Databases,” Journal of the ACM, 31:4, October 1984.Google Scholar
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    R. Reiter, “Towards a Logical Reconstruction of Relational Database Theory,” in M. Brodie, J. Myopoulos, and J. Schmidt (eds.), On Conceptual Modelling, Springer-Verlag, 1984.Google Scholar
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    M. Winslett, “A Model-Theoretic Approach to Updating Logical Databases,” Stanford Univ. Computer Science Dept. Tech. Report, January 1986. A preliminary version appeared as “A Model-Theoretic Approach to Updating Logical Databases (Extended Abstract),” Proc. of the 5th ACM PODS, Cambridge, March 1986.Google Scholar
  7. [Winslett 86b]
    M. Winslett, “Is Belief Revision Harder Than You Thought?”, Stanford Computer Science Dept. Tech. Report, June 1986. A shortened version will appear in Proc. AAAI Conference, Philadelphia, August 1986.Google Scholar

Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • Marianne Winslett
    • 1
  1. 1.Computer Science Dept.Stanford UniversityStanfordUSA

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