Building the Data Warehouse

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The aggregation of operational data into a single data warehouse record may take many forms; for example:


■■ Values taken from operational data can be summarized.


■■ Units of operational data can be tallied, where the total number of units is captured.


■■ Units of data can be processed to find the highest, lowest, average, and so forth.


■    First and last occurrences of data can be trapped.


■    Data of certain types, falling within the boundaries of several parameters, can be measured.


■    Data that is effective as of some moment in time can be trapped.


■    The oldest and the youngest data can be trapped.


The ways to perform representative aggregation of operational data are limitless.


Another very appealing benefit to the creation of profile records is organizing the data in a compact and convenient form for the end user to access and analyze. Done properly, the end user is quite comfortable with the distillation of many records into a single record because he or she has to look only in a single place to find what is needed. By prepackaging the data into an aggregate record in the data warehouse, the data architect saves the end user from tedious processing.


operational


customer

Customer/month


data warehouse


The monthly call records are aggregated in order to provide a single composite record.


Figure 3.43 The creation of a profile record from a series of detailed records.

Managing Volume


In many cases, the volume of data to be managed in the data warehouse is a significant issue. Creating profile records is an effective technique for managing the volume of data. The reduction of the volume of data possible in moving detailed records in the operational environment into a profile record is remarkable. It is possible (indeed, normal) to achieve a 2-to-3 order-of-magnitude reduction of data by the creation of profile records in a data warehouse. Because of this benefit, the ability to create profile records is a powerful one that should be in the portfolio of every data architect.

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