An approach to schema integration and query formulation in federated database systems

TLDR

The graphical language is grounded in algebraic theory. The paper introduces a language that enables schema integration and query formulation in federated database systems. The language augments the relational model with connectors and Bach algebraic operators, providing a diagrammatic representation and GUI that resolve schema incompatibilities using extended abstract data types.

Abstract

A language is introduced in which both schema integration and query formulation for federated database systems can be performed. The relational model is augmented with connectors that impose predicate conditions over attributes of relations either at the same or different sites. The relational model with connectors has a natural diagrammatic representation, and thus, the language has a graphical user interface. The theoretical foundation for the graphical language is algebraic. Bach algebraic operator maps a diagram (of relations with connectors) into another diagram, and every diagram represents a possible user query. Operators specifically designed to operate on incompatible schemas are introduced and formally defined. Possible domain incompatibilities are resolved by using extended abstract data types.