shuijian-xu
commented
5 years ago The value and importance of historical data are generally recognized. It has been observed that the ability to store historical data is one of the main advantages of data warehousing and that the absence of historical data, in operational systems, is one of the motivating factors in the development of data warehouses.
In data warehousing the addition of time enables historical data to be held and queried upon. This means that users of data warehouses can view aspects of their enterprise at any specific point or over any period of time for which the historical data is recorded.
This enables the observation of patterns of behavior over time so that we can make comparisons between similar or dissimilar periods, for example, this year versus last year, seasonal trends.
Armed with this information, we can extrapolate with the use of predictive models to assist us with planning and forecasting. We are, in effect, using the past to attempt to predict the future：If men could learn from history, what lessons it might teach us! But passion and party blind our eyes, and the light which experience gives is a lantern on the stern, which shines only on the waves behind us!