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JUCS
2010

Redundant Relations in Relational Databases: A Model Theoretic Perspective

8 years 6 months ago
Redundant Relations in Relational Databases: A Model Theoretic Perspective
: We initiate in this work the study of a sort of redundancy problem revealed by what we call redundant relations. Roughly, we define a redundant relation in a database instance (dbi) as a k-ary relation R such that there is a first-order query which evaluated in the reduced dbi, (i.e., the dbi without the redundant relation R) gives us R. So, given that first-order types are isomorphism types on finite structures, we can eliminate that relation R as long as the equivalence classes of the relation of equality of the first-order types for all k-tuples in the dbi are not altered. It turns out that in a fixed dbi, the problem of deciding whether a given relation in the dbi is redundant is decidable, though intractable, as well as the problem of deciding whether there is any relation symbol in the schema which is a redundant relation in the given dbi. We then study redundant relations with a restricted notion of equivalence so that the problem becomes tractable. Key Words: first-order type...
Flavio Antonio Ferrarotti, Alejandra Lorena Paolet
Added 20 May 2011
Updated 20 May 2011
Type Journal
Year 2010
Where JUCS
Authors Flavio Antonio Ferrarotti, Alejandra Lorena Paoletti, Jose Maria Turull Torres
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