On finding the optimal access path to resolve a relational data base query

  • P. Degano
  • A. Lomanto
  • F. Sirovich
Part of the Lecture Notes in Computer Science book series (LNCS, volume 88)


The paper presents a formal model to specify a data base, a query and the access path which must be followed to obtain the ansewer. The model is based on the problem reduction hypergraphs, for which an admissible and optimal search algorithm is known. An effective method is given to map the data base and the query into a problem reduction hypergraph, which the known search algorithm can be applied to. The optimal solution to the problem reduction hypergraph provides an optimal (and possibly parallel) program to obtain the answer to the given query. Since the model allows to determine the correct answer, if any, without modifications of the data base nor requiring further information, it is an improvement over the models presented in the literature.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1980

Authors and Affiliations

  • P. Degano
    • 1
  • A. Lomanto
    • 1
  • F. Sirovich
    • 2
  1. 1.Istituto di Scienze della InformazioneUniversità degli Studi C/so ItaliaPisa
  2. 2.Istituto di Elaborazione della Informazione — C.N.R.Pisa

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