Distributed Evaluation of the Datalog Query Language

  • Lars Stefan Jensen
  • Erik Johannes Kaae


We present a technique for distributed evaluation of the deductive database language datalog, that is, prolog without function symbols. Datalog is both a powerful extension of relational database query languages like sql and a suitable language for constructing expert systems. Both of these types of applications tend to be computationally complex and to exhibit parallelism of the kinds known as Or parallelism and All-solutions And parallelism. We therefore expect large speedup by exploiting this parallelism.

The lack of function symbols ensures a finite model, in spite of presence of recursive clauses. We therefore discuss how to ensure termination while retaining completeness. Our distributed implementation uses a top/down interpretation strategy and is based on the problem-heap paradigm and dynamic load balancing. Tests show up to 14.2 times speedup, obtained on a Transputer network containing 16 Transputers.


Deductive Database Unit Clause Parallel Evaluation Dynamic Load Balance DATALOG Program 
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/Wien 1990

Authors and Affiliations

  • Lars Stefan Jensen
    • 1
  • Erik Johannes Kaae
    • 1
  1. 1.Department of Computer ScienceTechnical University of DenmarkLyngbyDenmark

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