Semantic query optimization using inter-relational functional dependencies

Addresses the role of specific types of semantic constraints in the process of query optimization. A new type of dependency is introduced, called inter-relational functional dependency, which is an extension of functional dependencies to two or more relations having common attributes. A complete axiomatization is proposed with an O(n³) decision procedure. The importance of this concept is illustrated through semantic query simplification rules involving inter-relational functional dependencies as well as other types of dependencies. These rules are incorporated in a knowledge based system for performance optimization of a relational database