An improved join dependency for efficient constraint checking

  • K. P. Tan
  • T. C. Tan
Databases And Information Systems
Part of the Lecture Notes in Computer Science book series (LNCS, volume 497)


In a relational database model, checking the contraints of join dependency involves examining a set of n tuples and solving m1 constraint equalities. We derive a scheme called the (n,m)-JD in which the number of constraint equalities is reduced to m2, by forming cyclic combinations of the (disjoint) elements of the partition and increasing the number of intersection operations to obtain the projections in the constraint equalities. The reduced set of constraint equalities results in less elementary checking operations and hence an overall increase in efficiency in the normalization effort. The relationship among (n,m)-JDs of various degrees and orders is also studied and formalised.


Database design join dependency constraint checking 


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Copyright information

© Springer-Verlag Berlin Heidelberg 1991

Authors and Affiliations

  • K. P. Tan
    • 1
  • T. C. Tan
    • 1
  1. 1.Department of Information Systems and Computer ScienceNational University of SingaporeSingaporeSingapore

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