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FD Covers and Universal Complements of Simple Projections
Umeå University, Faculty of Science and Technology, Department of Computing Science.
2012 (English)In: Foundations of Information and Knowledge Systems -: 7th International Symposium, FoIKS 2012, Kiel, Germany, March 5-9, 2012. Proceedings / [ed] Thomas Lukasiewicz, Attila Sali, Heidelberg: Springer Berlin/Heidelberg, 2012, 184-202 p.Conference paper (Refereed)
Abstract [en]

The constant-complement strategy, in which the admissible updates to a given view are those which hold a second complementary view constant, remains one of the most attractive formalisms for identifying suitable translation mechanisms for updates to views of database schemata. However, in general, it suffers from the drawback that the reflections of view updates to the main schema can depend upon the choice of complement in various ways. To overcome this drawback completely, a special kind of complement, called a universal complement, is required. In this paper, sufficient conditions for the existence of such a complement are established for a classical but nevertheless very important setting — views defined by simple projection of a universal relational schema constrained by functional dependencies (FDs). Certain uniqueness properties of covers of these dependencies prove critical in the characterization. The results are extended to quasi-universal complements, which are unique up to exchange of equivalent attributes, thus recapturing certain situations for which unique covers do not exist.

Place, publisher, year, edition, pages
Heidelberg: Springer Berlin/Heidelberg, 2012. 184-202 p.
, Lecture Notes in Computer Science, ISSN 0302-9743 ; 7153
National Category
Computer Systems
URN: urn:nbn:se:umu:diva-53916DOI: 10.1007/978-3-642-28472-4_11ISBN: 978-3-642-28471-7OAI: diva2:514388
FoIKS 2012, Kiel, Germany, March 5-9, 2012
Available from: 2012-04-09 Created: 2012-04-09 Last updated: 2012-05-29Bibliographically approved

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