Catalogue management for a multidatabase system using an X.500 directory system

Multidatabase systems (MDBSs) provide applications with integrated access to a collection of databases. The component database systems are typically heterogeneous, distributed, autonomous and pre-existing. MDBSs, like conventional database management systems (DBMSs), require catalogue information to provide their services. The catalogue must be stored in a separate system database, or repository, since component databases are assumed to be independent of the MDBS. We examine the approach taken to catalogue management in the CORDS MDBS which uses an X.500 directory service to store the MDBS catalogue and discuss the advantages and disadvantages of this approach. Storing the MDBS catalogue in a directory service is an appealing approach but is an application for which the directory service was never intended. There are, therefore, practical problems which must be addressed including the suitability of the information model and the performance of the system for typical repository requests. We discuss the design of the CORDS MDBS catalogue and present a set of experiments we conducted with it to examine the performance and scalability of the approach.