Richard Hull Timothy Griffin ACM SIGMOD Conference 1997 26 2 231 242 1430 KB Previous approaches to supporting hypothetical queries have been eager : some representation of the hypothetical state (or the corresponding delta) is materialized, and query evaluation is filtered through that representation. This paper develops a frame Information Systems, DATABASE MANAGEMENT, Languages. Information Systems, DATABASE MANAGEMENT, Logical Design, Schema and subschema. Information Systems, DATABASE MANAGEMENT, Systems, Query processing. Information Systems, INFORMATION STORAGE AND RETRIEVAL, Information Search and Retrieval, Query formulation. Mathematics of Computing, MATHEMATICAL SOFTWARE, Algorithm design and analysis. Theory of Computation, LOGICS AND MEANINGS OF PROGRAMS, Semantics of Programming Languages. F.3.2 Theory of Computation, LOGICS AND MEANINGS OF PROGRAMS, Semantics of Programming Languages. G.4 Mathematics of Computing, MATHEMATICAL SOFTWARE, Algorithm design and analysis. H.2.1 Information Systems, DATABASE MANAGEMENT, Logical Design, Schema and subschema. H.2.3 Information Systems, DATABASE MANAGEMENT, Languages. H.2.4 Information Systems, DATABASE MANAGEMENT, Systems, Query processing. H.3.3 Information Systems, INFORMATION STORAGE AND RETRIEVAL, Information Search and Retrieval, Query formulation.