Spatial Data Warehouses - Data Warehouse Systems: Design and Implementation - page 454

users may be able to express what spatial data they require in order to
exploit the features of multidimensional models and to perform various kinds
of spatial analysis, and the design process may be performed following the
same steps as those for traditional data warehouse design.

a

Document
requirements
specification

Determine
analysis needs

Identify users

b Late inclusion of

spatial support

Add
spatial
support

Define final
conceptual
schema and
mappings

Define initial
conceptual
schema

Check data
availability and
specify mappings

Fig. 11.16 Steps of the analysis-driven approach for spatial data warehouses. ( a )
Requirements specification phase. ( b ) Conceptual design phase

The conceptual design phase (Fig. 11.16 b) starts with the development
of the initial spatial data warehouse schema. Note that this schema already
includes spatial elements since we assume that the users are able to refer
to spatial data when expressing their specific analysis needs. Therefore, we
follow the lower path of Fig. 11.16 b. In the following step, we must determine
whether the data are available in the source systems. Then, the corresponding
mappings with data warehouse elements must be specified. Note, however,
that external sources may be needed if the required spatial support does not
exist in the source systems. In the last step, the final schema is developed; it
includes all data warehouse elements for which the corresponding data exists
in the source systems (whether internal or external). Additionally, the final
mapping between the two kinds of systems is delivered.

Late Inclusion of Spatial Support

It may happen that users are not familiar with spatial data management
or that they prefer to start by expressing their analysis needs related to
nonspatial elements and include spatial support later on. In this case, the
requirements specification and conceptual-design phases proceed as for a
traditional data warehouse, ignoring spatial features until the initial schema
is checked with respect to the data available in the source systems. As