Building the Data Warehouse

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15.    How easy will it be to add more storage to the data warehouse environment at a later point in time? How easy will it be to reorganize data within the data warehouse environment at a later point in time?


ISSUE: No data warehouse is static, and no data warehouse is fully specified at the initial moment of design. It is absolutely normal to make corrections in design throughout the life of the data warehouse environment. To construct a data warehouse environment either where midcourse corrections cannot be made or are awkward to make is to have a faulty design.


16.    What is the likelihood that data in the data warehouse environment will need to be restructured frequently (i.e., columns added, dropped, or enlarged, keys modified, etc.)? What effect will these activities of restructuring have on ongoing processing in the data warehouse?


ISSUE: Given the volume of data found in the data warehouse environment, restructuring it is not a trivial issue. In addition, with archival data, restructuring after a certain moment in time often becomes a logical impossibility.


17.    What are the expected levels of performance in the data warehouse environment? Has a DSS service level agreement been drawn up either formally or informally?


ISSUE: Unless a DSS service-level agreement has been formally drawn up, it is impossible to measure whether performance objectives are being met. The DSS service level agreement should cover both DSS performance levels and downtime. Typical DSS service level agreements state such things as the following:

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