A DB2 federated database system enables users and applications to reference multiple database management systems or databases within a single SQL statement. For example, with DB2's federated database support, you can join data that is located in a DB2 Universal Database table, a DB2 for OS/390 table, and an Oracle 7 table. Statements of this type are called distributed requests.
Location transparency--separating the location of a data source from its network address--is achieved by assigning nicknames to all tables and views that will be involved in distributed request queries. A nickname consists of a user-defined name that is mapped to values that identify the physical address of a data source. Both the nickname and these values are stored in the federated server's local database system catalogs.
Federated database functionality is available for DB2 Enterprise Edition and DB2 Extended Enterprise Edition only.
For more information about federated database system concepts, see the Administration Guide, Design and Implementation.
Figure 3 illustrates a typical federated system environment.
Figure 3. DB2 Federated System
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