From Federated Databases to a Federated Data Warehouse System

Although Data Warehousing is regarded as a mature technology now, the definition of a federated architecture for Data Warehouse (DW) integration remains an open research question. This paper identifies requirements on a Federated DW System and proposes an architecture supporting the tightly coupled integration of heterogeneous data marts into a global, logical schema. In order to enable the processing of queries in the federation, our approach provides a Dimension Algebra (DA) and Fact Algebra (FA) to define the mappings between the global and local schemas. Moreover, we demonstrate how to apply DA and FA expressions for dimension and fact integration and explain the benefits of such an approach.