Abstract
A new decomposition theory for functional dependencies in the Relational Database Model is given. It uses a method to break up a relation into two subrelations whose union is the given relation. This horizontal decomposition is based on a new constraint: the conditional-functional dependency. It indicates how to decompose a relation into two restrictions of this relation. The only difference between the two subrelations is a functional dependency that holds in one subrelation but not in the other. Functional dependencies can be expressed as special conditional-functional dependencies.
The membership problem is solved for this new constraint, and also for another constraint, induced by the horizontal decomposition: the afunctional dependency.
An algorithm is described that performs the decomposition. It uses a new normal form: the Conditional Normal Form. The link between the horizontal- and the traditional vertical decomposition is explained.
This author is supported by the IWONL.
This is a preview of subscription content, log in via an institution.
Preview
Unable to display preview. Download preview PDF.
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, Dept. of Math., Univ. of Antwerp, Belgium, report 81-39, 1981.
De Bra P., Paredaens J., Horizontal Decompositions for Handling Exceptions to Functional Dependencies, CERT-82 workshop “Logical Bases for Data Bases”, France, 1982.
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.
Author information
Authors and Affiliations
Editor information
Rights and permissions
Copyright information
© 1983 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
De Bra, P., Paredaens, J. (1983). Conditional dependencies for horizontal decompositions. In: Diaz, J. (eds) Automata, Languages and Programming. ICALP 1983. Lecture Notes in Computer Science, vol 154. Springer, Berlin, Heidelberg. https://doi.org/10.1007/BFb0036898
Download citation
DOI: https://doi.org/10.1007/BFb0036898
Published:
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-12317-0
Online ISBN: 978-3-540-40038-7
eBook Packages: Springer Book Archive