The Role of Integrity Constraints in Database Interoperation

We present an approach to database interoperation that exploits the semantic information provided by integrity constraints defined on the component databases. We identify two roles of integrity constraints in database interoperation. First, a set of integrity constraints describing valid states of the integrated view can be derived from the constraints defined on the underlying databases. Moreover, local integrity constraints can be used as a semantic check on the validity of the specification of the integrated view. We illustrate our ideas in the context of an instance-based database interoperation paradigm, where objects rather than classes are the unit of integration. We introduce the notions of objectivity and subjectivity as an indication of whether a constraint is valid beyond the context of a specific database, and demonstrate the impact of