Abstract
A new decomposition theory for functional dependencies in the Relational Database Model is given. It uses a horizontal decomposition of a relation into two disjoint subrelations, of which the union is the given relation. This horizontal decomposition is based on a new constraint, the imposed-functional dependency (ifd), of which the conditional-functional dependency (cfd), introduced in a previous work, is a special case.
Functional dependencies can be expressed as special cfd's, (which themselves are special cases of ifd's). The horizontal decomposition induces another constraint: the afunctional dependency. The membership problem for mixed ifd's and ad's is solved, and a complete set of inference rules is given. The inheritance problem, i.e. the problem of determining which dependencies hold in the subrelations that result from a horizontal decomposition step, is shown to be solvable in polynomial time.
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References
Armstrong W., Dependency structures of database relationships, Proc. IFIP 74, North Holland, pp. 580–583, 1974.
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.
Bernstein P.A., Normalization and Functional Dependencies in the Relational Database Model, CSRG-60, 1975.
Codd E., Further normalizations of the database relational model, In Data Base Systems (R. Rustin, ed.) Prentice Hall, N.J., pp. 33–64, 1972.
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.
De Bra P., Paredaens J., Horizontal Decompositions for Handling Exceptions to Functional Dependencies, in “Advances in Database Theory”, Vol. II, pp. 123–144, 1983.
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.
Fagin R., Armstrong Databases, IBM RJ 3440, 1982.
Paredaens J., De Bra P., On Horizontal Decompositions, XP2-Congress, State Univ. of Pennsylvania, 1981.
Smith J., Smith D., Data base abstractions: Aggregation and generalization, ACM TODS, vol. 2.2, pp. 105–133, 1977.
Ullman J., Principles of Database Systems, Pitman, 1980.
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© 1985 Springer-Verlag Berlin Heidelberg
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De Bra, P. (1985). Imposed-functional dependencies inducing horizontal decompositions. In: Brauer, W. (eds) Automata, Languages and Programming. ICALP 1985. Lecture Notes in Computer Science, vol 194. Springer, Berlin, Heidelberg. https://doi.org/10.1007/BFb0015741
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DOI: https://doi.org/10.1007/BFb0015741
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