Building the Data Warehouse

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In the simplest case in a data warehouse, each operational activity important to the corporation will trigger a snapshot. In this case, there is a one-to-one correspondence between the business activities that have occurred and the number of snapshots that are placed in the data warehouse. When there is a one-to-one correspondence between the activities in the operational environment and the snapshots in the data warehouse, the data warehouse tracks the history of all the activity relating to a subject area.


Some Examples


An example of a simple snapshot being taken every time there is an operational, business activity might be found in a customer file. Every time a customer moves, changes phone numbers, or changes jobs, the data warehouse is alerted, and a continuous record of the history of the customer is made. One record tracks the customer from 1989 to 1991. The next record tracks the customer from 1991 to 1993. The next record tracks the customer from 1993 to the present. Each activity of the customer results in a new snapshot being placed in the data warehouse.


As another example, consider the premium payments on an insurance policy. Suppose premiums are paid semiannually. Every six months a snapshot record is created in the data warehouse describing the payment of the premium— when it was paid, how much, and so on.


Where there is little volume of data, where the data is stable (i.e., the data changes infrequently), and where there is a need for meticulous historical detail, the data warehouse can be used to track each occurrence of a business event by storing the details of every activity.

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