Building the Data Warehouse

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Typically, the initial data warehouse focuses on one of these functional areas: ■■ Finance ■■ Marketing ■■ Sales


Occasionally, the data warehouse’s first functional area will focus on one of these areas:


■    Engineering/manufacturing


■    Actuarial interests


Justifying Your Data Warehouse


There is no getting around the fact that data warehouses cost money. Data, processors, communications, software, tools, and so forth all cost money. In fact, the volumes of data that aggregate and collect in the data warehouse go well beyond anything the corporation has ever seen. The level of detail and the history of that detail all add up to a large amount of money.


In almost every other aspect of information technology, the major investment for a system lies in creating, installing, and establishing the system. The ongoing maintenance costs for a system are miniscule compared to the initial costs. However, establishing the initial infrastructure of the data warehouse is not the most significant cost—the ongoing maintenance costs far outweigh the initial infrastructure costs. There are several good reasons why the costs of a data warehouse are significantly different from the cost of a standard system:


■    The truly enormous volume of data that enters the data warehouse.


■    The cost of maintaining the interface between the data warehouse and the operational sources. If the organization has chosen an extract/transfer/load (ETL) tool, then these costs are mitigated over time; if an organization has chosen to build the interface manually, then the costs of maintenance skyrocket.


■    The fact that a data warehouse is never done. Even after the initial few iterations of the data warehouse are successfully completed, adding more subject areas to the data warehouse is an ongoing need.

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