Building the Data Warehouse

Скачать в pdf «Building the Data Warehouse»




parts


reject


history



shipment


arrival


history



shipment


breakage


history


Figure 6.35 Nonredundancy of nonkey data throughout the many tables that make up the detailed level of the data warehouse.


terms of snapshots of data, the foreign key relationships that are found are organized in terms of “artifacts” of relationships. For an in-depth explanation of artifacts of relationships, refer to the www.billinmon.com Tech Topic on the subject, found in the “References” section.


An issue that arises is whether to place all of the detailed tables—common and local—under the same technology, as shown in Figure 6.37. There are many good arguments for doing so One is that the cost of a single platform versus multiple platforms is much less. Another is that the cost of support and training will be less. In fact, about the only argument for multiple platforms for detailed data is that with multiple platforms, there may not be the need for a single massively large platform, and as a consequence, the cost of the multiple smaller platforms may be less than a single larger platform. In any case, many organizations adopt the strategy of a single platform for all their detailed data warehouse data, and the strategy works well.


Other Types of Detailed Data


Another strategy is to use different platforms for the different types of data found at the detailed level. Figure 6.38 shows one example of this option. Some of the local data is on one platform, the common data is on another platform, and other local data is on yet another. This option is certainly one that is valid,

Скачать в pdf «Building the Data Warehouse»