On global query optimization in multidatabase systems

Abstract

Multidatabase management systems (MDBMS) enable data sharing among heterogenous local databases (component databases) and thus provide interoperability required by diverse applications. In multidatabase systems, user requests data from the multidatabase by posing non-procedural queries. For a query involving more than one database, a global optimization should be performed to achieve a good overall system performance. This article discusses global query optimization, one of the main reasons that the significant differences among the optimization problem for multidatabase and the distributed homogeneous system are not well recognized.