Implement a DB2 federated system, which acts as an application server in which data can reside in various sources but be exposed as a virtual database for querying by client applications. With a federated system, you can send distributed requests to multiple data sources within a single SQL statement.
Issues and Alternatives
IBM DB2 allows access to data sources through its various pre-built wrappers and by allowing the implementation of custom wrappers. The use of the pre-built ODBC wrapper allows the DB2 to pass portions of a SQL query down to an ODBC/SQL enabled data source for processing.
Use OpenAccess SDK to implement a custom ODBC driver, allowing you to expose any data source as a virtual SQL database and enabling IBM DB2 to access it for processing distributed queries.
See Integrate Any Data Source with IBM DB2 through ODBC Wrapper (.pdf)
Quickly implement an enterprise quality custom ODBC driver for an efficient federated DBMS