is a logical collection of information gathered from many different operational databases that supports business analysis activities and decision making tasks. The primary purpose of a data warehouse is to aggregate information throughout an organization into a single repository in such a way that employees can make decisions and undertake business analysis activities. Therefore, while databases store the details of all transactions (for instance, the sale of a product) and events (hiring a new employee), data warehouses store that same information but in an aggregated form more suited to supporting decision making tasks. Aggregation, in this instance, can include totals, counts, averages, and the like. Because of this sort of aggregation, data warehouses support only analytical processing.