Horizontal decompositions based on functional-dependency-setimplications

  • P. De Bra
Contributed Papers
Part of the Lecture Notes in Computer Science book series (LNCS, volume 243)


A new approach towards horizontal decompositions in the Relational Database Model is given. It is based on partial implications between sets of functional dependencies. This horizontal decomposition theory is especially useful for databases which must represent “real world” situations, in which there always are exceptions to rather severe constraints like functional dependencies (fd's).

The functional-dependency-set-implication (fsi) generalizes all previous work on horizontal decompositions using partial implications between (single) fd's.

The exceptions to a set of fd's are formalized using another new constraint, the anti-functional-dependency-set (afs). The membership problem is solved for mixed fsi's and afs', and a complete set of inference rules is given. The inheritance problem, i.e. which dependencies hold in the (two) subrelations generated by the horizontal decomposition) is shown to be solvable in polynomial time.


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  1. [Ar]
    Armstrong W., Dependency structures of database relationships, Proc. IFIP 74, North Holland, pp. 580–583, 1974.Google Scholar
  2. [Be]
    Beeri C., Bernstein P.A., Computational Problems related to the Design of Normal Form Relation Schemes, ACM TODS, vol. 4.1, pp. 30–59, 1979.Google Scholar
  3. [Ber]
    Bernstein P.A., Normalization and Functional Dependencies in the Relational Database Model, CSRG-60, 1975.Google Scholar
  4. [Co]
    Codd E., Further normalizations of the database relational model, In Data Base Systems (R. Rustin, ed.) Prentice Hall, N.J., pp. 33–64, 1972.Google Scholar
  5. [De1]
    De Bra P., Paredaens J., The membership and the inheritance of functional and afunctional dependencies, Proc. of the Colloquium on Algebra, Combinatorics and Logic in Computer Science, Gyor, Hungary.Google Scholar
  6. [De2]
    De Bra P., Paredaens J., Horizontal Decompositions for Handling Exceptions to Functional Dependencies, in “Advances in Database Theory”, Vol. II, pp. 123–144, 1983.Google Scholar
  7. [De3]
    De Bra P., Paredaens J., Conditional Dependencies for Horizontal Decompositions, in “Lecture Notes in Computer Science”, Vol. 154, pp. 67–82, (10-th ICALP), Springer-Verlag, 1983.Google Scholar
  8. [De4]
    De Bra P., Imposed-Functional Dependencies Inducing Horizontal Decompositions, in “Lecture Notes in Computer Science”, Vol. 194, pp. 158–170, (12-th ICALP), Springer-Verlag, 1985.Google Scholar
  9. [De5]
    De Bra P., Functional Dependency Implications, Inducing Horizontal Decompositions, UIA-report 85-30, 1985.Google Scholar
  10. [Fa]
    Fagin R., Armstrong Databases, IBM RJ 3440, 1982.Google Scholar
  11. [Pa]
    Paredaens J., De Bra P., On Horizontal Decompositions, XP2-Congress, State Univ. of Pennsylvania, 1981.Google Scholar
  12. [Ul]
    Ullman J., Principles of Database Systems, Pitman, 1980.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1986

Authors and Affiliations

  • P. De Bra
    • 1
  1. 1.Department of MathematicsUniversity of Antwerp, U.I.A.AntwerpBelgium

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