Federated database system

A federated database system is a type of meta-database management system (DBMS) which transparently integrates multiple autonomous database systems into a single federated database. The constituent databases are interconnected via computer network, and may be geographically decentralized. Since the constituent database systems remain autonomous, a federated database system is a contrastable alternative to the (sometimes daunting) task of merging together several disparate databases.

Through data abstraction, federated database systems can provide a uniform front-end user interface, enabling users to store and retrieve data in multiple databases with a single query--even if the constituent databases are heterogeneous. To this end, a federated database system must be able to deconstruct the query into subqueries for submission to the relevant constituent DBMS's, after which the system must composite the result sets of the subqueries.

Because various database management systems employ different query languages, federated database systems can apply wrappers to the subqueries to translate them into the appropriate query languages.