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DATA WAREHOUSING FUNDAMENTALS: A Comprehensive Guide for IT Professionals by Paulraj Ponniah

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5.1. CHAPTER OBJECTIVES

  • Discuss how and why defining requirements is different for a data warehouse

  • Understand the role of business dimensions

  • Learn about information packages and their use in defining requirements

  • Review methods for gathering requirements

  • Grasp the significance of a formal requirements definition document

A data warehouse is an information delivery system. It is not about technology, but about solving users' problems and providing strategic information to the user. In the phase of defining requirements, you need to concentrate on what information the users need, not so much on how you are going to provide the required information. The actual methods for providing information will come later, not while you are collecting requirements.

Most of the developers of data warehouses come from a background of developing operational or OLTP (online transactions processing) systems. OLTP systems are primarily data capture systems. On the other hand, data warehouse systems are information delivery systems. When you begin to collect requirements for your proposed data warehouse, your mindset will have to be different. You have to go from a data capture model to an information delivery model. This difference will have to show through all phases of the data warehouse project.

The users also have a different perspective about a data warehouse system. Unlike an OLTP system which is needed to run the day-to-day business, no immediate payout is seen in a decision support system. The ...

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