Range Nesting: A Fast Method to Evaluate Quantified Queries

Abstract

Database queries explicitly containing existentialand universal quantification become increasingly importantin a number of areas such as integrity checking, interactionof databases, and statistical databases. Using aconcept of range nesting in relational calculus expressions,the paper describes evaluation algorithms and transformationmethods for an important class of quantified relational calculusqueries called perfect expressions. This class includeswell-known classes of "easy" queries such as tree queries(with free and existentially quantified variables only), andcomplacent (disconnected) queries.