Note also in Figure 3-7 that there are three tables dealing with products:
DimProduct, DimProductCategory, and DimProductSubcategory. This is an example
of snowflaking, as described earlier in this chapter. These snowflaked tables will be
addressed shortly in order to simplify the view.
52 B u s i n e s s I n t e l l i g e n c e w i t h M i c r o s o f t O f f i c e P e r f o r m a n c e P o i n t S e r v e r 2 0 0 7
After choosing the tables and views that will make up the DSV, the developer
is presented with a graphical image of the DSV. This image is a schema diagram
that matches the tables and views chosen in the wizard, and may look extremely
complicated, depending on the number of items selected when creating the DSV.
Figure 3-8 shows the DSV generated for the tables chosen in Figure 3-7.
Note that this doesn??™t look like a typical star schema because there are two
fact tables in it. DSV diagrams become wildly more complex as tables are added,
especially when there are multiple fact tables. Fortunately, there is a way to create
new diagrams that show only a subset of the tables. A good practice is to create one
diagram per fact table. Each of those diagrams will then show that fact table and just
the dimensions upon which that fact table relies. This means that developers will
have a series of easier-to-use star schemas to work with as the process unfolds.
DSVs have additional features as well, two of which are the Named Query and
the Named Calculation.
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