The presence of time and the dependence upon it is one of the things that sets data warehouse applications apart from traditional operational systems. Most business applications are suited to operating in the present environment where time does not require special treatment. In many cases, dates are no more than descriptive attributes. In a data warehouse, time affects the very structure of the system. The temporal requirements of a data warehouse are very different from those of an operational system, yet it is the operational system that feeds information about changed data to the data warehouse.
The presence of time and the dependence upon it is one of the things that sets data warehouse applications apart from traditional operational systems. Most business applications are suited to operating in the present environment where time does not require special treatment. In many cases, dates are no more than descriptive attributes. In a data warehouse, time affects the very structure of the system. The temporal requirements of a data warehouse are very different from those of an operational system, yet it is the operational system that feeds information about changed data to the data warehouse.