Query folding with inclusion dependencies

Query folding 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 databases. The power of query folding can be considerably enhanced by taking into account integrity constraints that are known to hold on base relations. This paper describes an extension of query folding that utilizes inclusion dependencies to find foldings of queries that would otherwise be overlooked. We describe a complete strategy for finding foldings in the presence of inclusion dependencies and present a basic algorithm that implements that strategy. We also describe extensions to this algorithm when both inclusion and functional dependencies are considered.