Building the Data Warehouse

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In Figure 6.5, a local data warehouse exists for different geographical regions or for different technical communities. The local data warehouse serves the same function that any other data warehouse serves, except that the scope of the data warehouse is local. For example, the data warehouse for Brazil does not have any information about business activities in France. Or the data warehouse for car parts does not have any data about motorcycles. In other words, the local data warehouse contains data that is historical in nature and is integrated within the local site. There is no coordination of data or structure of data from one local data warehouse to another.


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Figure 6.5 Some circumstances in which you might want to create a two-tiered level of data warehouse.


The Global Data Warehouse


Of course, there can also be a global data warehouse, as shown in Figure 6.6. The global data warehouse has as its scope the corporation or the enterprise, while each of the local data warehouses within the corporation has as its scope the local site that it serves. For example, the data warehouse in Brazil does not coordinate or share data with the data warehouse in France, but the local data warehouse in Brazil does share data with the corporate headquarters data warehouse in Chicago. Or the local data warehouse for car parts does not share data with the local data warehouse for motorcycles, but it does share data with the corporate data warehouse in Detroit. The scope of the global data warehouse is the business that is integrated across the corporation. In some cases, there is considerable corporate integrated data; in other cases, there is very little. The global data warehouse contains historical data, as do the local data warehouses. The source of the data for the local data warehouses is shown in Figure 6.7, where we see that each local data warehouse is fed by its own operational systems. The source of data for the corporate global data warehouse is the local data warehouses, or in some cases, a direct update can go into the global data warehouse.

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