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Datalog as a Query Language for Data Exchange Systems

  • Marcelo Arenas
  • Pablo Barceló
  • Juan Reutter
Part of the Lecture Notes in Computer Science book series (LNCS, volume 6702)

Abstract

The class of unions of conjunctive queries (UCQ) has been shown to be particularly well-behaved for data exchange; its certain answers can be computed in polynomial time (in terms of data complexity). However, this is not the only class with this property; the certain answers to any Datalog program can also can be computed in polynomial time. The problem is that both UCQ and Datalog do not allow for negated atoms, while most database query languages are equipped with negation. Unfortunately, adding an unrestricted form of negation to these languages yields to intractability of the problem of computing certain answers.

In order to face this challenge, we have recently proposed a language, called Datalog C( ≠ ) [5], that extends Datalog with a restricted form of negation while keeping the good properties of Datalog, and UCQ, for data exchange. In this article, we provide evidence in favor of the use of Datalog C( ≠ ) as a query language for data exchange systems. More precisely, we introduce the syntax and semantics of Datalog C( ≠ ), we present some of the fundamental results about this language shown in [5], and we extend those results to the case of data exchange settings that allow for constraints in the target schema. All of these results provide justification for the use of Datalog C( ≠ ) in practice.

Keywords

Polynomial Time Data Exchange Query Language Conjunctive Query Universal Solution 
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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Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  • Marcelo Arenas
    • 1
  • Pablo Barceló
    • 2
  • Juan Reutter
    • 3
  1. 1.Dept. of Computer SciencePontificia Universidad Católica de ChileChile
  2. 2.Dept. of Computer ScienceUniversity of ChileChile
  3. 3.School of InformaticsUniversity of EdinburghUK

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