International Business Machines Corporation
Access-plan-based querying for federated database-management systems

Abstract:

A federated database-management system receives an SQL query or other type of data-access request. The federated system's host DBMS parses, rewrites, and optimizes the request into an optimal data-access plan, then determines which portions of the plan require access to data stored on the federated systems' remote databases. The federated host partitions the plan into subplans that each represent instructions of the original data-access request that were directed to a corresponding remote database of the federated DBMS. Each subplan is then transmitted to its corresponding remote database, which directly executes the subplan and returns results to the host. If necessary, a subplan is translated from an original generic access-plan format into a database-specific format required by its corresponding remote database.