Building the Data Warehouse

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The data profiles that can be created during the data-monitoring process include the following:


■■ A catalog of all tables in the warehouse ■■ A profile of the contents of those tables ■■ A profile of the growth of the tables in the data warehouse ■■ A catalog of the indexes available for entry to the tables


■    A catalog of the summary tables and the sources for the summary


The need to monitor activity in the data warehouse is illustrated by the following questions:


■    What data is being accessed?


■    When?


■■ By whom?


■    How frequently?


■    At what level of detail?


■    What is the response time for the request?


■    At what point in the day is the request submitted?


■    How big was the request?


■■ Was the request terminated, or did it end naturally?


Response time in the DSS environment is quite different from response time in the online transaction processing (OLTP) environment. In the OLTP environment, response time is almost always mission critical. The business starts to suffer immediately when response time turns bad in OLTP. In the DSS environment there is no such relationship. Response time in the DSS data warehouse environment is always relaxed. There is no mission-critical nature to response time in DSS. Accordingly, response time in the DSS data warehouse environment is measured in minutes and hours and, in some cases, in terms of days.


Just because response time is relaxed in the DSS data warehouse environment does not mean that response time is not important. In the DSS data warehouse environment, the end user does development iteratively. This means that the next level of investigation of any iterative development depends on the results attained by the current analysis. If the end user does an iterative analysis and the turnaround time is only 10 minutes, he or she will be much more productive than if turnaround time is 24 hours. There is, then, a very important relationship between response time and productivity in the DSS environment. Just because response time in the DSS environment is not mission critical does not mean that it is not important.

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