Dimension Table Details
Now that we’ve walked through the four-step process, let’s return to the dimension tables and focus on populating them with robust attributes.
Date Dimension
The date dimension is a special dimension because it is the one dimension nearly guaranteed to be in every dimensional model since virtually every business process captures a time series of performance metrics. In fact, date is usually the first dimension in the underlying partitioning scheme of the database so that the successive time interval data loads are placed into virgin territory on the disk.
For readers of the first edition of The Data Warehouse Toolkit (Wiley, 1996), this dimension was referred to as the time dimension. However, for more than a decade, we’ve used the “date dimension” to mean a daily grained dimension table. This helps distinguish between date and time-of-day dimensions.
Unlike most of the other dimensions, you can build the date dimension table...