Bill Inmon, ‘the so-called father of modern data warehousing,’ 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.” That is, characteristically, data warehouses provide a unified view of all data elements with a common definition and representation for all business units; data are stored with a subject orientation that facilitates multiple views of the data and facilitates decision-making; data are recorded with a historical perspective in mind, and hence, a time dimension is added to facilitate data analysis and time comparisons; once data are properly stored, it cannot be changed but only updated periodically; operational data is aggregated into summaries when needed; and data is often redundant (Turban et al, 2005; Westerman, 2001; Rob & Coronel, 2004).