There are four different stages of the Data Warehousing lifecycle...

Offline Operational Databases : Data warehouses in this initial stage are developed by simply copying the database of an operational system to an off-line server where the processing load of reporting does not impact the operational system's performance.

Offline Data Warehouse : Data warehouses in this stage of evolution are updated on a regular time cycle (usually daily, weekly or monthly) from the operational systems, and the data is stored in an integrated reporting oriented data structure.

Real-Time Data Warehouse : Data warehouses at this stage are updated on a transaction or event basis, every time an operational system performs a transaction (e.g. an order or a delivery or a booking).

Integrated Data Warehouse : Data warehouses at this stage are used to generate activity or transactions that are passed back into the operational systems for use in the daily activity of the organization.