The external database in SICStus Prolog

  • Hans Nilsson
System Descriptions
Part of the Lecture Notes in Computer Science book series (LNCS, volume 624)


The SICStus External Database implements an efficient way of storing general Prolog terms (possibly with variables) on disk. They can be retrieved with indexing on user specified parts of the terms. The indexing is a constant-time operation, and the total fetch time is slightly better than a linear function of the size. The algorithm is an improved version of superimposed codewords. Dynamic hashing is used for storage. Some performance data is given.


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  1. 1.
    Mats Carlsson et al. Industrial SICStus Prolog User's Manual. Swedish Institute of Computer Science, 1990.Google Scholar
  2. 2.
    Department of Computer Science, University of Melbourne. NU-Prolog, Reference Manual, May 1987.Google Scholar
  3. 3.
    R. J. Enbody and H.C. Du. Dynamic hashing schemes. ACM Computing Surveys, 20(2), June 1988.Google Scholar
  4. 4.
    Hans Nilsson. The external storage facility in SICStus Prolog. Technical Report SICS R91:13 ISRN SICS-R-91/13-SE, Swedish Institute of Computer Science, October 1991.Google Scholar
  5. 5.
    Kotagiri Ramamohanarao and John Shepard. A superimposed codeword indexing scheme for very large prolog databases. In Proceedings of the third International Conference of Logic Programming, July 1986.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1992

Authors and Affiliations

  • Hans Nilsson
    • 1
  1. 1.Computer Science LaboratoryELLEMTEL ABÄlvsjöSweden

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