Data Warehouse Concepts - Data Warehouse Systems: Design and Implementation - page 51

Chapter 3
Data Warehouse Concepts
This chapter introduces the basic concepts of data warehouses. A data
warehouse is a particular database targeted toward decision support. It
takes data from various operational databases and other data sources and
transforms it into new structures that fit better for the task of performing
business analysis. Data warehouses are based on a multidimensional model,
where data are represented as hypercubes, with dimensions corresponding to
the various business perspectives and cube cells containing the measures to be
analyzed. In Sect. 3.1 , we study the multidimensional model and present its
main characteristics and components. Section 3.2 gives a detailed description
of the most common operations for manipulating data cubes. In Sect. 3.3 ,we
present the main characteristics of data warehouse systems and compare them
against operational databases. The architecture of data warehouse systems
is described in detail in Sect. 3.4 . As we shall see, in addition to the data
warehouse itself, data warehouse systems are composed of back-end tools,
which extract data from the various sources to populate the warehouse, and
front-end tools, which are used to extract the information from the warehouse
and present it to users. In Sect. 3.5 , we introduce the design methodology
we will use throughout the topic. We finish by describing in Sect. 3.6 two
representative business intelligence suite of tools, SQL Server and Pentaho.
3.1 Multidimensional Model
The importance of data analysis has been steadily increasing from the early
1990s, as organizations in all sectors are being required to improve their
decision-making processes in order to maintain their competitive advantage.
Traditional database systems like the ones studied in Chap. 2 do not satisfy
the requirements of data analysis. They are designed and tuned to support
the daily operations of an organization, and their primary concern is to ensure