Semantic Optimization of 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). We present here a number of semantic optimization techniques applicable to preference queries. The techniques make it possible to remove redundant occurrences of the winnow operator and to apply a more efficient algorithm for the computation of winnow. We also study the propagation of integrity constraints in the result of the winnow. We have identified necessary and sufficient conditions for the applicability of our techniques, and formulated those conditions as constraint satisfiability problems.

• Type: Conference
• Year: 2004
• Where: CDB
• Authors: Jan Chomicki
• Keywords: CDB 2004, Database, Preference Queries, Semantic Optimization Techniques, Winnow Operator