Databases Reference
In-Depth Information
or that new application can get its Sales, Product, or Customer data from
the data warehouse, which will allow the business unit sponsoring the
new application to avoid the expenditures, expenses, and investments,
reduce the budget, and increase the ROI of that new application and the
business unit that sponsored it. Only one option is the obvious and pre-
ferred option: when data is available in a data warehouse, get that data
from the data warehouse. That is the gravitational pull of data.
The data in a data warehouse will “pull” or “draw” applications needing
data to itself. As a result, the ROI of the data warehouse will reflect the
expenses necessary to provide data to applications without the benefit of
that data; in addition, the ROI of the applications will reflect the benefit of
that data without the expenses necessary to obtain that data. One applica-
tion leveraging the data in a data warehouse is company. Fifty new appli-
cations per year is a crowd. Any data warehouse that draws that kind of a
crowd will inevitably find that some portion of those applications, as they
grow and change, will try to modify the data, structure, and architecture
of a data warehouse to match their growth and change. Such modifica-
tions can convert an enterprise data warehouse into an application data
warehouse. This is when a successful and growing data warehouse can
become its own problem through the gravitational pull of its own data.
A data warehouse can also be the small object that is drawn to a larger
object. When a ten-ton elephant wants to sit in your front yard, where does
it sit? Your front yard. There's no stopping it. When a ten-ton business
unit wants to use the data in a data warehouse…well, you can guess what
is about to happen. That business unit is going to use the data in the data
warehouse. The ten-ton business unit is going to require the data ware-
house supplement the data already in the data warehouse with additional
data; furthermore, the ten-ton business unit may want to design the addi-
tional data necessary to meet the purposes of the business unit, which may
or may not be the purposes of the data warehouse. Data already in the data
warehouse may be redesigned to meet the needs of the ten-ton business
unit, possibly to the detriment of the data warehouse.
Why is the ten-ton business unit consuming the data warehouse in this
way? The answer is the same for the ten-ton business unit as for the small
single application. Any expense or investment that can be migrated from
the ten-ton business unit to the data warehouse will increase the ROI of
the ten-ton business unit. Any economy that robs Peter to pay Paul will
continue to be supported by Paul. Likewise, an enterprise that allows a
business unit to migrate its expenses to a data warehouse, but experience
