Ralph Kimball处理慢速变化维的方法

One major difference between an OLTP system and a data warehouse is the ability to accurately describe the past. OLTP systems are usually very poor at correctly representing a business as of a month or a year ago. A good OLTP system is always evolving. O rders are being filled and, thus, the order backlog is constantly changing. Descriptions of products, suppliers, and customers are constantly being updated, usually by overwriting. The large volume of data in an OLTP system is typically purged every 90 t o 180 days. For these reasons, it is difficult for an OLTP system to correctly represent the past. In an OLTP system, do you really want to keep old order statuses, product descriptions, supplier descriptions, and customer descriptions over a multiyear p eriod?   (Full Text: http://www.dbmsmag.com/9604d05.html)