Proven Portals: Best Practices for Planning, Designing, and Developing Enterprise Portals

Characteristics of Data Warehouses

Data warehouses have several distinguishing characteristics.

• These systems combine data from multiple sources. Operational systems such as ERP systems provide production data, financial systems supply revenue and expense data, and human resource systems present employee data.

• The data copied into a data warehouse does not change (except to correct errors). The data warehouse is a historical record of the state of an organization. The frequent changes of the source OLTP systems are reflected in the data warehouse by adding new data, not by changing existing data.

• Data warehouses are subject oriented, that is, they focus on measuring entities, such as sales, inventory, and quality. OLTP systems, by contrast, are ...