Much of the conversation about what constitutes a data warehouse has been driven by two influential thought leaders $$ Bill Inmon and Ralph Kimball $$ who have different approaches to modeling and developing warehouses. Inmon defines a data warehouse as $$a subject$-$oriented, integrated, time$-$variant and non$-$volatile collection of data in support of management$$s decision$-$making process.$64$ A normalized relational model is used to store and manage data. Kimball defines a warehouse as $$a copy of transaction data specifically structured for query and analysis.$$ Kimball$$s approach calls for a dimensional model.