Users can guide query optimization by selecting from a wide range of control choices.
We present a comprehensive view of the system from broad design goals, the language, and the architecture, to language interfaces and implementation details. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the VLDB copyright notice and the title of the publication and its date appear, and notice is given that copying is by the permission of the Very Large Data Base Endowment. Key Words Deductive database, query language, logic programming system. A Generalization of the Differential Approach to Recursive Query Evaluation. Set Constructors in a Logic Database Language.