DATA WAREHOUSING FUNDAMENTALS: A Comprehensive Guide for IT Professionals

5.2. DIMENSIONAL ANALYSIS

In several ways, building a data warehouse is very different from building an operational system. This becomes notable especially in the requirements gathering phase. Because of this difference, the traditional methods of collecting requirements that work well for operational systems cannot be applied to data warehouses.

5.2.1. Usage of Information Unpredictable

Let us imagine you are building an operational system for order processing in your company. For gathering requirements, you interview the users in the Order Processing department. The users will list all the functions that need to be performed. They will inform you how they receive the orders, check stock, verify customers' credit arrangements, price the order, determine the shipping arrangements, and route the order to the appropriate warehouse. They will show you how they would like the various data elements to be presented on the GUI (graphical user interface) screen for the application. The users will also give you a list of reports they would need from the order processing application. They will be able to let you know how and when they would use the application daily.

In providing information about the requirements for an operational system, the users are able to give you precise details of the required functions, information content, and usage patterns. In striking contrast, for a data warehousing system, the users are generally unable to define their requirements clearly. They cannot ...