Source-aware Multidatabase Query Processing

We introduce a multidatabase model to represent the information that derives from different local databases. This model, known as Tuple-Source (TS) relational model, accommodates tuples from different local databases by attaching them with their source information in the global relations which are also known as TS-relations. In other words, a source attribute is implicit in every TS-relation. To manipulate the global relations, we have developed the TSSQL query language and implemented a distributed query processor to process such queries. In this paper, we report our distributed query processing architecture and algorithms. Our architecture consists of a query mediator and a number of query agents, one for each local database. By encapsulating the heterogeneous query interfaces to different local databases within the query agents, we allow a generic query processing strategy to be adopted by the query mediator. Our approach further ensures that local autonomy is preserved. 1 Introduct..