Data warehousing is the segregating of operations information into related forums in order to increase the efficiency of reporting processes while, at the same time, preventing the decrease in productivity that comes from reporting from the main computer system. By duplicating selected portions of data into related systems, reports can be created in real time without slowing day to day operations. A data warehouse can be a simple duplicate of all information held on a separate computer system or it can be a working duplicate that is updated as each transaction takes place.