CHAPTER 5 DEFINING THE BUSINESS REQUIREMENTS
CHAPTER OBJECTIVES
CHAPTER OBJECTIVES
- Discuss how and why defining requirements is different for data warehouse
- Understand the rote of business dimensions
- Learn about information packages and the 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 arc 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 front a data capture model to an information delivery model. This difference will have to show through all phases of the data ware-home 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 users do not sec a compelling need to use a decision supports system whereas they cannot refrain from using an operational system. Without which they cannot run their business.
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.
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 arc 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 front a data capture model to an information delivery model. This difference will have to show through all phases of the data ware-home 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 users do not sec a compelling need to use a decision supports system whereas they cannot refrain from using an operational system. Without which they cannot run their business.
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.
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