Advanced Dimension Design - Professional SQL Server Analysis Services 2005 with MDX - page 318

Overview

In this look at advanced dimension design, you learn to aggregate data up to
the parent member through custom rollup operations and learn about the ef-
fects of dimension and hierarchy properties. Also, you learn about business in-
telligence wizards which help you enhance dimensions. Finally, you are intro-
duced to dimension writeback, which is a way to make changes to dimension
members for "what" if analysis. Consider first the details you already learned
about dimension design back in Chapter 5 ; you learned how dimensions,
which are made up of hierarchies, consist of tiers called levels. The two types
of hierarchies were described, both attribute and multi-level hierarchies, and
the Time dimension and Parent-Child dimensions were discussed in some de-
tail.

Here you learn about the ways you can leverage and extend dimensions to get
even more value out of them. Normally, you would expect the data to be ag-
gregated to its parent. For example, if you have a hierarchy such as Time, then
Sales per month will be rolled up to calculate first the Sales of a quarter, and
Sales Quarters will be rolled up to calculate the Sales of a year. Even though
this is the most common way a user would expect the data to be aggregated,
there are dimensions in which the data does not get rolled up by a simple sum.
Another take-away from Chapter 5 was that parent-child hierarchies are spe-
cial, and Analysis Services 2005 provides properties that help enhance dimen-
sions that contain parent-child hierarchies.

If you don't get the in-depth details of this chapter just from reading the narrat-
ive descriptions, don't worry; the concepts are demonstrated through examples
as well. This area is a classic example of "It seems profoundly difficult until you
get it, but once you get it, it is so simple as to seem obvious." If you already
know the concepts mentioned above or otherwise understood them after read-
ing this paragraph, read the chapter anyway, it goes far beyond the basics.

If you came to this chapter looking for information on calcu-
lated members or Data Mining dimensions, both being per-
fectly reasonable to expect here, well, they are not covered
here. For information on Calculated Members, please see
Chapter 3 and for Data Mining dimensions, please see
Chapter 14 .

Important