Concept based design of data warehouses: The DWQ demonstrators

The ESPRIT Project DWQ(Foundations of Data Warehouse Quality) aimed at impr oving the quality of DW design and operation through systematic enrichment of the semantic foundations of data warehousing. Logic-based knowledge repr esentation and reasoning techniques were developed to control accuracy, con sistency, and completeness via advanced conceptual modeling techniques for source integration, data reconciliation, and multi-dimensional aggregation. This is complemented by quantitative optimization techniques for view mate rialization, optimizing timeliness and responsiveness without losing the se mantic advantages from the conceptual approach. At the operational level, q uery rewriting and materialization refreshment algorithms exploit the knowl edge developed at design time. The demonstration shows the interplay of the se tools under a shared metadata repository, based on an example extracted from an application at Telecom Italia.