Construction and Maintenance of Heterogeneous Data Warehouses - Data Warehousing Design and Advanced Engineering Applications - page 192

and non-volatile collection of data in support of
management's decision making process (Inmon,
1995).A heterogeneous DW is a one whose sources
are heterogeneous.
Our theoretical approach allows us the integra-
tion of various heterogeneous data sources (DS)
(Hamdoun, 2006; Hamdoun, Boufarès & Badri,
2007; Badri, 2008). This approach takes as an
input an integration environment (see figure 2)
as a set of DS and a set of relationships between
them and returns a DW. Because it deals with
heterogeneous data, our approach proposes an
unified formal theoretical representation of them.
It is general and applicable for any kind of inte-
gration. We will be able for instance to duplicate
databases or to create several versions of databases
(Hamdoun, 2006; Hamdoun, Boufarès & Badri,
2007; Badri, 2008).
During several years, DW maintenance was
considered as a real-time processing operation
and many works (O'Gorman, Agrawal & El Ab-
badi,1999; Zhang & Rundensteiner, 2000; Lau-
rent, Lechtenborger, Spyratos & Vossen, 2001)
proposed algorithms and techniques to solve
and manage concurrent DW updates. Since we

believe that the special need of using DW does
not has a transactional nature. And these last
years, some DW maintenance works (Rantzau,
Constantinescu, Heinkel & Meinecke, 2002;
Engstrom, Chakravarthy & Lings, 2003) focused
on the heterogeneity of DS. They used mapping
solutions (from XML to relational or vice versa).
A state of the art can be found (Badri, Boufarès,
Ducateau & Gargouri, 2005).
In this chapter, we are interested in the data
integration with the aim of building and then
of maintaining heterogeneous warehouses. It is
structured as follows. Section 2 deals with the
heterogeneous data integration. We introduce vari-
ous data sources (relational, object-relational and
XML) and propose a generic model to represent
them (Hamdoun, 2006; Hamdoun, Boufarès &
Badri, 2007; Badri, 2008).
We also present the integration environment
as well as the different steps of the integration
process. Two possible physical architectures for
the heterogeneous DW (Badri, Boufarès & Heiwy,
2007) are presented in the third section. Section 4
presents our incremental maintenance method to
integrate updates incoming from heterogeneous

Figure 2. Example of an integration environment