Building the Data Warehouse

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A variant of a wholesale replacement is the conversion of some or all of an existing operational system. This approach works on a limited basis, where the existing system is small and simple. The larger and more complex the existing operational system, the less likelihood that the system can be converted.

access the operation of seeking, reading, or writing data on a storage unit.

access method a technique used to transfer a physical record from or to a mass storage device.

access pattern the general sequence in which the data structure is accessed (for example, from tuple to tuple, from record to record, from segment to segment, etc.).

accuracy a qualitative assessment of freedom from error or a quantitative measure of the magnitude of error, expressed as a function of relative error.

ad hoc processing one-time-only, casual access and manipulation of data on parameters never before used, usually done in a heuristic, iterative manner.

after image the snapshot of data placed on a log on the completion of a transaction.

agent of change a motivating force large enough not to be denied, usually aging of systems, changes in technology, radical changes in requirements, etc.

algorithm a set of statements organized to solve a problem in a finite number of steps.

alternate storage storage other than disk-based storage used to hold bulk amounts of relatively inactive storage.

analytical processing using the computer to produce an analysis for management decision, usually involving trend analysis, drill-down analysis, demographic analysis, profiling, etc.

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