Figure 1: Implementing a “logical” data model within a Data Warehouse. This figure illustrates how the “logical” data structure within the D/W serves as a means of insulating our “specialized
views” of data from changes in our operational packaged applications or legacy systems. For example, let’s assume the 8 “specialized views” of data shown above within our D/W all include data
originating from System X. If we were to discontinue System X, we would only have to change the “logical” transformation program to extract data from the system that was replacing System X. None of
the “specialized” transformation programs would need to be altered. The result is substantial long-term savings in terms of ongoing maintenance costs associated with the data warehouse environment.
(Note: the “logical” model also simplifies creation of summarized data structures (not shown).)
