A system, method, and program storage device implementing the method, for integrating data in a database management system, wherein the method comprises grouping data sources and replicas of the data sources that provide analogous data into a common logical domain; writing application queries against the common logical domain; selecting a correct set of replicas of the data sources and a query-execution strategy for combining a content of the correct set of replicas of the data sources in order to answer the application queries according to query-cost-based optimization; selecting a correct set of data sources according to run-time constraints; shielding the application queries from changes to the data sources by dynamically binding the application queries against the correct sets of data sources and replicas of the data sources; and processing the application queries by generating an optimum query result based on the steps of grouping and shielding.