Semantic optimization techniques for preference queries

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Semantic optimization techniques for preference queries
Preference queries are relational algebra or SQL queries that contain occurrences of the winnow operator (find the most preferred tuples in a given relation). Such queries are parameterized by specific preference relations. Semantic optimization techniques make use of integrity constraints holding in the database. In the context of semantic optimization of preference queries, we identify two fundamental properties: containment of preference relations relative to integrity constraints and satisfaction of order axioms relative to integrity constraints. We show numerous applications of those notions to preference query evaluation and optimization. As integrity constraints, we consider constraint-generating dependencies, a class generalizing functional dependencies. We demonstrate that the problems of containment and satisfaction of order axioms can be captured as specific instances of constraintgenerating dependency entailment. This makes it possible to formulate necessary and suffici...
Jan Chomicki
Added 15 Dec 2010
Updated 15 Dec 2010
Type Journal
Year 2007
Where IS
Authors Jan Chomicki
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