Rewriting queries using views with access patterns under integrity constraints

Abstract

We study the problem of rewriting queries using views in the presence of access patterns, integrity constraints, disjunction, and negation. We provide asymptotically optimal algorithms for finding minimal containing and maximal contained rewritings and for deciding whether an exact rewriting exists. We show that rewriting queries using views in this case reduces (a) to rewriting queries with access patterns and constraints without views and also (b) to rewriting queries using views under constraints without access patterns. We show how to solve (a) directly and how to reduce (b) to rewriting queries under constraints only (semantic optimization). These reductions provide two separate routes to a unified solution for all three problems, based on an extension of the relational chase theory to queries and constraints with disjunction and negation. We also handle equality and arithmetic comparisons. © 2005 Springer-Verlag.