Fig. 15.1.9 Transformation.

The transformation of data as they move from the application environment to the data
warehouse environment is one where the measurement and definitions of data are
altered. As a simple example, data in the application environment are measured in inches,
while data in the data warehouse are measured in centimeters. As data pass from the
application environment to the data warehouse, the calculation of converting data from
inches to centimeters is made.

The transformation of data from the data warehouse to the data mart is a different kind of
transformation. Typically, this transformation is made in the selection and calculation of
data. As a simple example, the data warehouse holds data about all customers. Only the
customers from Missouri are selected and then only customers who have spent more than
$1000 a month. Then, data about these selected customers are then added together and
placed in the data mart.

Other Data Than the System of Record

Another interesting point is as follows: is there data in the application environment or the
data warehouse or the big data environment that is not part of the system of record? The
answer is absolutely yes—there are data in those places that are not part of the system of
record. And it is perfectly all right to access and use that data. However, for extreme

Chapter 15.1: The System of Record