Query rewriting using views in the presence of functional and inclusion dependencies

Query rewriting using views is a technique for determining how a query may be answered using a given set of resources, which may include materialized views, cached results of previous queries, or queries answerable by other d atabases. The power of query rewriting can be considerably enhanced by taki ng into account integrity constraints that are known to hold on base relati ons. This paper describes an extension of query rewriting that utilizes inc lusion dependencies to find rewritings of queries that would otherwise be o verlooked. We describe a complete strategy for finding rewritings in the pr esence of inclusion dependencies and present a basic algorithm that impleme nts that strategy. We also describe extensions to this algorithm when both inclusion and functional dependencies are considered. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.