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BIAnalytix Tip Summary: Data Mart vs. Data Warehouse

Data Mart Defined
A data mart is a decision support system that is designed to support a given department within a larger organization, the Human Resources business unit for example. Data marts are typical housed on hardware owned and supported by the business units for which they are intended; they have data that is stored only at a grain that the BU demands, and this data is often kept at some level of aggregation. The sources for data marts are sometimes the corporate data warehouse, and if the source is an originating transaction system, there are typically no more than one or two involved. Concisely, the data mart is a subject specific, tactical store that is of interest to few users outside of the owning BU.

Data Warehouse Defined
A data warehouse is a decision support system that is designed to support most if not all aspects of a corporate entity. Data warehouses are installed on hardware owned and supported by corporate IT. They contain data at an un-aggregated grain in order to cover any and all possible needs regarding drill down and data mining. A data warehouse will contain as much history as is available from the various source systems and will typically be populated from between five to dozens of transactional and operational systems. As one would expect, the combination of low grain, years of history, and enterprise spanning scope is a recipe for huge quantities of data.