Database Reference
In-Depth Information
Data Warehousing
Since the mid1990s, database technology has expanded into a new area of interest — the
development and management of data warehouses. It is a fascinating field of study that
deserves some attention. This chapter provides an overview of data warehousing and
information extraction. The chapter proceeds under the following subheadings:
•
Introduction
•
Rationale For Data Warehousing
•
Characteristics of a Data Warehouse
•
Data Warehouse Architectures
•
Extraction, Transformation and Loading
•
Summary and Concluding Remarks
24.1 Introduction
The concept of a data warehouse springs from the combination of two sets of needs:
•
The business requirement for a global view of information,
independent of and despite its source or underlying structure
•
The need of information systems (IS) professionals to manage
large volumes of company data in a more effective manner
The data warehouse has been approached many times and from many directions in
the last decade; many implementations exist today. In order to proceed, we must make a
distinction between data and information:
•
Data is the computerized representation of business information.
•
Information is the assimilation of data to convey meaning as
understood and used by end users.
A data warehouse is an
integrated, subject-oriented, time-variant, nonvolatile,
consistent database, constructed from multiple sources, and made available (in the form
of read-only access) to support decision making in a business context. As you will soon
see (in section 24.3), the highlighted terms in this definition are deliberate because of
their significance.
