In Chapter 2 Retail Sales of Ralph Kimball's The Data Warehouse Toolkit, the author describes a date dimension with three fields which appear totally alien to me:
Date Key (PK) Date Full Date Description Day of Week **Day Number in Epoch** **Week Number in Epoch** **Month Number in Epoch** Day Number in Calendar Month Day Number in Calendar Year ...
I understand that an Epoch is the "instance in time chosen as a particular era" and that the current standard epoch for J2000.0 starts on January 1, 2000. But I don't see how these numbers would be helpful in a date dimension or a cube used for getting information about retail sales.
- Are numbers in Epoch typically used in Date Dimensions?
- What Epoch would be used for a modern day business?
- How would a user slice data based on Epoch and why?