About the Series ...
article is a member of the series Introduction to MSSQL Server 2000
Analysis Services. The series is designed to provide hands-on
application of the fundamentals of MS SQL Server 2000 Analysis Services,
with each installment progressively adding features and techniques designed to
meet specific real - world needs. For more information on the series, as well
as the hardware / software requirements to prepare for the exercises we
will undertake, please see my initial article, Creating Our First
Note: Service Pack 3 updates are assumed for MSSQL Server 2000, MSSQL
Server 2000 Analysis Services, and the related Books Online
and Samples. Images are from a Windows 2003 Server
environment, upon which I have also implemented MS Office 2003, but the
steps performed in the articles, together with the views that result, will be quite
similar within any environment that supports MSSQL
Server 2000 and MSSQL
Server 2000 Analysis Services ("Analysis Services" or "MSAS").
The same is generally true, except where differences are specifically noted,
when MS Office 2000 and above are used in the environment, in cases
where MS Office components are presented in the article.
In this article, we will continue the exploration of distinct counts we began in our previous article, Distinct
Count Basics: Two Perspectives. Having discussed why distinct counts are useful,
and often required, within the design of robust analysis and reporting
applications, we described some of the challenges that are inherent in distinct
counts. We then undertook practice exercises to illustrate general solutions
to meet example business requirements, providing an approach afforded us by the
MSAS user interface, and then an alternative approach we enacted using MDX.
Our stated purpose was to lay the framework for this and subsequent articles,
where we will focus upon specific scenarios that occur commonly in the business
environment, within which the optimal use of distinct counts can become
a very real consideration.
In this article, we will examine one approach to the efficient
use of DISTINCT COUNT within our applications: We will focus upon the
optimization of DISTINCT COUNT through the isolation of the DISTINCT COUNT
attributes into a separate cube, and show how this represents one of the
more efficient approaches to optimizing the related functionality. To
accomplish our objectives, we will undertake the following steps in this
Set the stage
by providing a hypothetical business requirement;
requirement with an MDX query that contains DISTINCT COUNT;
performance of the query in general;
separate cube to house the DISTINCT COUNT attributes of our solution;
Combine the new
DISTINCT COUNT cube with the previously existing cube, through the
creation of a virtual cube in MSAS;
Create a new
query, targeting the virtual cube as its source, to return a dataset
identical to that returned by our initial query;
Comment upon performance
gains in executing the new query upon the new cube combination.