INTEGRITY CONSTRAINT INTEGRATION IN HETEROGENEOUS DATABASES - AN ENHANCED METHODOLOGY FOR SCHEMA INTEGRATION

In today's technologically diverse corporate environment, it is common to find several different databases being used to accomplish the orga nization's operational data management functions. Providing interopera bility among these databases is important to the successful operation of the organization. One approach to providing interoperability among heterogeneous database systems, is to define one or more schemas which represent a coherent view of the underlying databases. In the past, m ost approaches have used schematic knowledge about the underlying data bases to generate integrated representations of the databases. In this paper we present a seven step methodology for utilizing integrity con straint knowledge from heterogeneous databases. Specifically, we descr ibe how we can generate a set of integrity constraints applicable at t he integrated level from constraints specified on local databases. We introduce the concept of constraint-based relationships between object s in heterogeneous databases and describe the role that these relation ships play in integrity constraint integration. Finally, we describe h ow the integrated set of constraints generated using our methodology c an be used to facilitate semantic query processing in a heterogeneous database environment. (C) 1997 Elsevier Science Ltd. All rights reserv ed.