A federated system allows you to send distributed requests to multiple data sources within a single SQL statement. A federated system consists of a DB2 instance that operates as a server, a database that acts as the federated database, one or more data sources, and clients (users and applications) who will access the database and data sources. With a federated system, you can send distributed requests to multiple data sources with a single SQL statement.

To users and client applications, data sources appear as a single collective database. Users and applications work with the federated database that is within the federated server. The federated database contains catalog entries that identify data sources and their characteristics. The federated server accesses the information stored in the federated database system catalog to determine the best plan for processing SQL statements.