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Author Ginsburg, Seymour ♦ Hull, Richard
Source ACM Digital Library
Content type Text
Publisher Association for Computing Machinery (ACM)
File Format PDF
Copyright Year ©1986
Language English
Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Abstract The notion of sort set is introduced here to formalize the fact that certain database relations can be sorted so that two or more columns are simultaneously listed in order. This notion is shown to be applicable in several ways to enhance the efficiency of an implemented database. A characterization of when order dependency implies the existence of sort sets in a database is presented, along with several corollaries concerning complexity, Armstrong relations, and cliques of certain graphs. Sort-set dependencies are then introduced. A (finite) sound and complete set of inference rules for sort-set dependencies is presented, as well as a proof that there is no such set for functional and sort-set dependencies taken together. Deciding logical implication for sort-set dependencies is proved to be polynomial, but if functional dependencies are included the problem is co-NP-complete. Each set of sort-set and functional dependencies is shown to have an Armstrong relation. A natural generalization of Armstrong relation, here called $\textit{separator},$ is given and then used to study the relationship between order and sort-set dependencies.
ISSN 00045411
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 1986-05-01
Publisher Place New York
e-ISSN 1557735X
Journal Journal of the ACM (JACM)
Volume Number 33
Issue Number 3
Page Count 24
Starting Page 465
Ending Page 488

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Source: ACM Digital Library