Database Reference
In-Depth Information
We now have the exact result we wanted: members of the role can only see data
for Canada.
What is the price of checking this box? It is potentially a high one. As we know,
Analysis Services makes extensive use of aggregations during query processing to
improve performance. If we use the Enable Visual Totals option, aggregations at
granularities above the hierarchy we set it on can no longer be used because they
contain values calculated using the entire hierarchy and not the subset of it that the
role exposes. This means that when Analysis Services receives a query that contains
the All Member on the Sales Territory Country attribute or any member above it, it
will not be able to use certain aggregations and so performance may be worse. It's
worth pointing out that there are situations where the Enable Visual Totals box can
remain unchecked, for example, because the need to display unfiltered values at
higher granularities is greater than any potential security concerns.
Let's now take a look at some of the other options on the Advanced tab of the
Dimension Data security window. We can see in the preceding screenshot that
there are three panes. The first two let us define an MDX set of allowed and denied
members; this is simply the MDX representation of the selections made on the Basic
tab that we discussed earlier: the role will have access to all of the members in the
allowed set except for any members specified in the denied set. The third pane lets
us define a default member on the hierarchy specifically for the role, which may be
necessary when the role denies access to the original default member.
 
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