??? Modeling.ETL:.ETL is a cornerstone of the data warehousing process, and its
design and implementation may easily take 50% of the total time for setting up
a DW. In the literature some approaches were devised for conceptual modeling
of the ETL process from either the functional (Vassiliadis, Simitsis, & Skiadopoulos,
2002), the dynamic (Bouzeghoub, Fabret, & Matulovic, 1999), or
the static (Calvanese, De Giacomo, Lenzerini, Nardi, & Rosati, 1998) points
of view. Recently, also some interesting work on translating conceptual into
logical ETL schemata has been done (Simitsis, 2005). Nevertheless, issues
such as the optimization of ETL logical schemata are not very well understood.
Besides, there is a need for techniques that automatically propagate changes
occurred in the source schemas to the ETL process.
Conclusion
In this chapter we have proposed a set of solutions for conceptual modeling of a DW
according to the DFM. Since 1998, the DFM has been successfully adopted, in real
Conceptual Modeling Solutions for the Data Warehouse 2
Copyright ?© 2007, Idea Group Inc. Copying or distributing in print or electronic forms without written permission
of Idea Group Inc. is prohibited.
DW projects mainly in the fields of retail, large distribution, telecommunications,
health, justice, and instruction, where it has proved expressive enough to capture
a wide variety of modeling situations.
Pages:
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82