Building the Data Warehouse

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■■ The shorter the cycle of the feedback loop, the more successful the warehouse effort. Once the DSS analyst makes a good case for changes to the data warehouse, those changes need to be implemented as soon as possible.

■■ The larger the volume of data that has to be changed, the longer the feedback loop takes. It is much easier to change 10 gigabytes of data than 100 gigabytes of data.

Failing to implement the feedback loop greatly short-circuits the probability of success in the data warehouse environment.

Strategic Considerations

Figure 9.5 shows that the path of activities that have been described addresses the DSS needs of the organization. The data warehouse environment is designed and built for the purpose of supporting the DSS needs of the organization, but there are needs other than DSS needs.

Figure 9.6 shows that the corporation has operational needs as well. In addition, the data warehouse sits at the hub of many other architectural entities, each of which depends on the data warehouse for data.

In Figure 9.6, the operational world is shown as being in a state of chaos. There is much unintegrated data and the data and systems are so old and so patched they cannot be maintained. In addition, the requirements that originally shaped the operational applications have changed into an almost unrecognizable form.

The migration plan that has been discussed is solely for the construction of the data warehouse. Isn’t there an opportunity to rectify some or much of the operational “mess” at the same time that the data warehouse is being built? The answer is that, to some extent, the migration plan that has been described presents an opportunity to rebuild at least some of the less than aesthetically pleasing aspects of the operational environment.

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