When designing a federated database, consider the following design topics:
Typically, the data accessible from a federated database is not stored at that database. References to data source tables and views are stored within the system catalog, but the actual data is located at the data source. As such, a federated database might need less storage space than a conventional database. This general rule might not apply if your queries, due to collating system differences or lack of function at a data source, must be executed locally. In this case, tables are materialized at DB2 for processing.
Because the majority of federated system data is typically located at one or more data sources located across a network, consider changing the resources assigned to DB2 and your network system. You might see performance increases after allocating more resources to the network at the DB2 system, than to the database manager itself.