The complexity of evaluating tuple generating dependencies

  • Authors:

  • Reinhard Pichler;Sebastian Skritek

  • Affiliations:

  • Vienna University of Technology;Vienna University of Technology

  • Venue:
  • Proceedings of the 14th International Conference on Database Theory
  • Year:
  • 2011

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Abstract

Dependencies have played an important role in database design for many years. More recently, they have also turned out to be central to data integration and data exchange. In this work we concentrate on tuple generating dependencies (tgds) which enforce the presence of certain tuples in a database instance if certain other tuples are already present. Previous complexity results in data integration and data exchange mainly referred to the data complexity. In this work, we study the query complexity and combined complexity of a fundamental problem related to tgds, namely checking if a given tgd is satisfied by a database instance. We also address an important variant of this problem which deals with updates (by inserts or deletes) of a database: Here we have to check if all previously satisfied tgds are still satisfied after an update. We show that the query complexity and combined complexity of these problems are much higher than the data complexity. However, we also prove sufficient conditions on the tgds to reduce this high complexity.