Dimension Role-Playing in Employee Comp Reporting
The employee hierarchy table is just one physical table, with a date range to keep employee’s employment history. This same employee hierarchy table can be used sometimes to show different business functional teams, for example, LAS VS. Underwriters on the same fact table.
I can simply create two SQL views to handle this, or just use two sub-queries if I don’t want to create too many SQL views.
This is called dimension role-playing. Role-playing in a data warehouse occurs when a single dimension simultaneously appears several times in the same fact table. The underlying dimension exists as a single physical table, but each of the roles should be presented in a separated labeled view.
Another common example in the employee productivity reporting, is the date dimension. We will just need one single date dimension table, but very often, we need to have a second date, such as application date, besides the primary decision date, on the same fact table. Again we only need to create two different SQL views to handle this, with only one underlying physical date dimension table.
