EXTENDED NESTED RELATIONS

This paper describes a conceptual framework for nested relational quer y processing using ''tuple identifiers.'' It does this by introducing extended nested relations, relations in which ''tuple identifiers'' ar e allowed as attribute values, and by defining two primitives, Index a nd Lookup, that allow query processing based on extensive use of tuple identifiers. Some properties of Index and of the flat relational data base that it induces are studied in detail.