On the decomposition of join dependencies

M. Gyssens, J. Paredaens

Onderzoeksoutput: Hoofdstuk in Boek/Rapport/CongresprocedureHoofdstukAcademicpeer review


In an earlier paper we proposed an algorithm for decomposing join dependencies (jds) in a relational database, using "hinges." Decomposing a jd can be useful for separating cyclic and acyclic parts of jds, obtaining more insight into the structure of a jd or making integrity checking more efficient. The Hinge Decomposition Algorithm has many desirable properties. However, in general it cannot generate all the decompositions of a given jd. Hence we cannot be sure that the Hinge Decomposition Algorithm generates the decomposition that is most suitable for the purposes it has to serve. Therefore, after reviewing the Hinge Decomposition Algorithm and its most important properties, we introduce unambiguous jds. We show that decomposable unambiguous jds are characterized by the property that they have exactly one decomposition satisfying some elementary desirable properties (union and intersection properties). Furthermore, this decomposition can be obtained with the Hinge Decomposition Algorithm. Finally, we characterize this decomposition in terms of the structure of the original jd. To prove our results, we make extensive use of hypergraph theory.
Originele taal-2Engels
TitelThe Theory of Databases
RedacteurenP.C. Kanellakis
Plaats van productieGreenwich CT
UitgeverijJAI Press
ISBN van geprinte versie0-89232-611-5
StatusGepubliceerd - 1986

Publicatie series

NaamAdvances in Computing Research
ISSN van geprinte versie0741-9341


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