A data warehouse is a repository (collection of resources that can be accessed to retrieve information) of an organization’s electronically stored data, designed to facilitate reporting and analysis. This definition of the data warehouse focuses on data storage . the main source of the data is cleaned, transformed and cataloged and is made available to be used by managers and other business professional for data mining, online analytical processing , market research and decision support(maracas & Obrien 2009) . However, the means to retrieve and analyze data, to extract, transform and load data, and to manage the data dictionary are also considered essential components of a data warehousing systems. Many references to data warehousing use this broader context. Thus, and expanded definition for data warehousing includes business intelligence tools to extract transform and load data into the repository, and tools to mange and retrieve metadata.