Databases Reference
In-Depth Information
time
dimension from
month
to
quarter
, or, say, drill down along the
location
dimension
from
country
to
city
.
Concept hierarchies can be used to
generalize
data by replacing low-level values
(such as “day” for the
time
dimension) by higher-level abstractions (such as “year”),
or to
specialize
data by replacing higher-level abstractions with lower-level values.
4.3
Data Warehouse Design and Usage
“What goes into a data warehouse design? How are data warehouses used? How do data
warehousing and OLAP relate to data mining?”
This section tackles these questions. We
study the design and usage of data warehousing for information processing, analyti-
cal processing, and data mining. We begin by presenting a business analysis framework
for data warehouse design (Section 4.3.1). Section 4.3.2 looks at the design process,
while Section 4.3.3 studies data warehouse usage. Finally, Section 4.3.4 describes
multi-
dimensional data mining
, a powerful paradigm that integrates OLAP with data mining
technology.
4.3.1
A Business Analysis Framework for Data
Warehouse Design
“
What can business analysts gain from having a data warehouse?
” First, having a data
warehouse may provide a
competitive advantage
by presenting relevant information
from which to measure performance and make critical adjustments to help win over
competitors. Second, a data warehouse can enhance business
productivity
because it is
able to quickly and efficiently gather information that accurately describes the organi-
zation. Third, a data warehouse facilitates
customer relationship management
because it
provides a consistent view of customers and items across all lines of business, all depart-
ments, and all markets. Finally, a data warehouse may bring about
cost reduction
by
tracking trends, patterns, and exceptions over long periods in a consistent and reliable
manner.
To design an effective data warehouse we need to understand and analyze busi-
ness needs and construct a
business analysis framework
. The construction of a large
and complex information system can be viewed as the construction of a large and
complex building, for which the owner, architect, and builder have different views.
These views are combined to form a complex framework that represents the top-down,
business-driven, or owner's perspective, as well as the bottom-up, builder-driven, or
implementor's view of the information system.
Four different views regarding a data warehouse design must be considered: the
top-
down view
, the
data source view
, the
data warehouse view
, and the
business query view
.
