Building the Data Warehouse

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The data warehouse then provides a foundation of integrated historical information that is available to the business analyst. This affinity between the data warehouse and the Web is shown in Figure 10.3.

Web environment

Figure 10.3 shows that data passes out of the data warehouse into the corporate operational data store (ODS), where it is then available for direct access from the Web. At first glance, it may seem odd that the ODS sits between the data warehouse and the Web. There are some very good reasons for this positioning.

data warehouse

The ODS is a hybrid structure that has some aspects of a data warehouse and other aspects of an operational system. The ODS contains integrated data and can support DSS processing. But the ODS can also support high-performance transaction processing. It is this last characteristic of the ODS that makes it so valuable to the Web.

When a Web site accesses the ODS, the Web environment knows that it will receive a reply in a matter of milliseconds. This speedy response time makes it possible for the Web to perform true transaction processing. If the Web were to directly access the data warehouse, it could take minutes to receive a reply from the warehouse. In the world of the Internet, where users are highly sensitive to response time, this would be unacceptable. Clearly, the data warehouse is not designed to support online response time. However, the ODS is designed for that purpose. Therefore, the direct input into the Web environment is the ODS, as seen by Figure 10.4.

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