Building the Data Warehouse

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life


customer


policy



premium


casualty


applications    subjects


Figure 2.1 An example of a subject orientation of data.


fed it is converted, reformatted, resequenced, summarized, and so forth. The result is that data—once it resides in the data warehouse—has a single physical corporate image. Figure 2.2 illustrates the integration that occurs when data passes from the application-oriented operational environment to the data warehouse.


Design decisions made by applications designers over the years show up in different ways. In the past, when application designers built an application, they never considered that the data they were operating on would ever have to be integrated with other data. Such a consideration was only a wild theory. Consequently, across multiple applications there is no application consistency in encoding, naming conventions, physical attributes, measurement of attributes, and so forth. Each application designer has had free rein to make his or her own design decisions. The result is that any application is very different from any other application.


Data is entered into the data warehouse in such a way that the many inconsistencies at the application level are undone. For example, in Figure 2.2, as far as


integration


operational


appl A m,f —


appl B 1,0 —


appl C x,y —


appl D male, female


data warehouse


encoding


m,f




attribute measurement


appl A appl B appl C appl D



pipeline—cm _ pipeline—inches pipeline—mcf pipeline—yds



pipeline—cm







multiple sources



description


description


description

Скачать в pdf «Building the Data Warehouse»