Federated Data Warehouses

Federated Data Warehouses are a collection of autonomous and often heterogeneous Data Marts (DM). When attemping to integrate autonomous DMs, data designers commonly face numerous conflicts that must be repaired. This book chapter analyzes and classifies the conflicts at the schema and instance level among dimensions and cubes in a systematic way, based on a formal data model. It shows the dependencies between dimension and cube integration and presents a methodological DM integration approach. A running example demonstrates how to repair the various heterogeneities. Moreover, the chapter introduces a Federated DW reference architecture enabling tightly coupled integration of autonomous DMs.