Oracle Tips  by Burleson Consulting

The Data Warehouse Development Life Cycle

The Project Delivery Schedule            

In order to accelerate the delivery times for a data warehouse project, a Project Evaluation and Review Technique (PERT) chart or a Critical Path Method (CPM) chart must be developed to identify those tasks that fall onto the critical path for the system. PERT was developed in the 1960s by the U.S. Navy to manage their Polaris submarine projects. Both PERT and CPM involve identifying tasks that fall onto the critical path for a system. A critical path task is a task for which there is no slack time. Hence, if the critical path task is delayed, the delivery time for the entire project is delayed. Conversely, if the delivery time for the critical path task is accelerated, then the delivery of the entire project is faster. It is a critical management skill for the data warehouse project manager to constantly identify those task that lie on the critical path.

As time is reported after development is underway, data warehouse managers may see that the critical path changes. It is not uncommon to misjudge time estimates for tasks, especially when the project involves a new technology. A project manager must be diligent in identifying tasks on the critical path. The second component involves identifying the necessary skill sets for each task. Remember, at any given time, there will only be a few tasks that lie on the critical path. The rest of the tasks have slack time and can be delayed without affecting the overall project delivery time. Consequently, managers can usually re-allocate resources away from non-critical tasks to critical tasks, thereby crashing the task on the critical path and speeding the delivery of the overall system. Of course, there are limitations. Consider the old adage: If one woman can have a baby in nine months, nine women should be able to have a baby in one month. There comes a time in every development project where we see a diminishing rate of return when adding resources, and it is indeed true that “too many cooks spoil he broth.” The key for the successful data warehouse project manager is determining when the point of diminishing return has been reached.

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This is an excerpt from "High Performance Data Warehousing". To learn more about Oracle, try "Oracle Tuning: The Definitive Reference", by Donald K. Burleson.  You can buy it direct from the publisher at 30% off here:
http://www.rampant-books.com/book_1002_oracle_tuning_definitive_reference_2nd_ed.htm