This approach is, in our view, more difficult to pursue than the previous one. Nevertheless,
it is the only alternative when a detailed analysis of data sources cannot be made
(for instance, when the DW is fed from an ERP system), or when the sources come
from legacy systems whose complexity discourages recognition and normalization.
Mixed.Approaches
Finally, also a few mixed approaches to design have been devised, aimed at joining
the facilities of data-driven approaches with the guarantees of requirement-driven
ones (Bonifati, Cattaneo, Ceri, Fuggetta, & Paraboschi, 2001; Giorgini et al., 2005).
Here the user requirements, captured by means of a goal-oriented formalism, are
matched with the schema of the source database to drive the algorithm that generates
the conceptual schema for the DW. For instance, the approach proposed by
Giorgini et al. (2005) encompasses three phases:
1. Create, in the Tropos formalism, an organizational model that represents the
stakeholders, their relationships, their goals, as well as the relevant facts for
the organization and the attributes that describe them.
Conceptual Modeling Solutions for the Data Warehouse 2
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2. Create, in the Tropos formalism, a decisional model that expresses the analysis
goals of decision makers and their information needs.
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