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  • Gross margin - dense vs. sparse block evaluation mode in MDX

    Gross margin (also known as Gross profit margin or Gross profit rate) is defined as (Revenue – Cost of Sales)/Revenue. In terms of Adventure Works sample database we can write this in MDX as [Gross Margin] = ([Measures].[Internet Sales Amount] - [Measures].[Internet Total Product Cost]) / [Measures].[Internet Sales Amount]; While this ...
    Posted to Microsoft OLAP by Mosha Pasumansky (Weblog) by mosha on November 1, 2008
  • Optimizing order of sets in MDX crossjoins

    For scalar values a*b is the same as b*a. (although we saw that performance of these two could be different in MDX in “Performance of multiplication in MDX” article). But if a and b are sets, then obviously results are different – since the order of tuples in the resulting set will be different. But does it matter if we were to perform some other ...
    Posted to Microsoft OLAP by Mosha Pasumansky (Weblog) by mosha on October 24, 2008
  • Optimizing MDX aggregation functions

    One of the most significant changes in Analysis Services 2008 was improving performance of MDX queries and calculations. In particular, query optimizer can choose block (a.k.a. subspace) computation mode in query plan more often than in AS2005, and usually using block/subspace computation mode brings performance orders of magnitude better than ...
    Posted to Microsoft OLAP by Mosha Pasumansky (Weblog) by mosha on October 22, 2008
  • Get most out of partition slices

    Setting partition slice has always been an important optimization technique in Analysis Services. Every presentation talked about it and every whitepaper mentioned it, for example the Microsoft SQL Server 2000 Analysis Services Performance Guide contains a chapter appropriately named “Define the Data Slice for Each Partition”, here is a quote from ...
    Posted to Microsoft OLAP by Mosha Pasumansky (Weblog) by mosha on October 14, 2008
  • Product Volatility: Optimizing MDX with MDX Studio

    In this article we will show how to take typical, everyday MDX and optimize it by simply following advices of MDX Studio Analyzer. As a starting point, I will take “Product Volatility” example as published by Thomas Ivarson in his blog. It is a perfect example, because Thomas took a real business problem, and implemented it using very clean and ...
    Posted to Microsoft OLAP by Mosha Pasumansky (Weblog) by mosha on July 29, 2008
  • MDX and partitioning

    Partitions have been a built-in feature of Analysis Services ever since the first version. Naturally, all the engine subsystems, including the MDX query optimizer, work well with partitions. There are rare cases, however, when over-aggressive prefetching can generate query plan which is not optimal with respect to the partitioning scheme. ...
    Posted to Microsoft OLAP by Mosha Pasumansky (Weblog) by mosha on December 18, 2007
  • Optimizing Count(Filter(...)) expressions in MDX

    As the readers of my blog know, bulk evaluation mode (called ''block computation mode'' in Katmai) delivers much better performance in MDX than the cell-by-cell evaluation mode. Therefore the most important optimization technique with MDX in Analysis Services is to rewrite MDX in such a way that makes block computations possible. Easy to say, ...
    Posted to Microsoft OLAP by Mosha Pasumansky (Weblog) by mosha on November 22, 2007
  • Notes about Notes from Microsoft BI Conference

    I was reading the blog post ''My notes from Microsoft BI Conference'' by Vidas Matelis. It is a collection of notes recorded at different presentations, chalk talks etc. I felt that I agree with some of them, disagree with some, and have no opinion about some. I felt like it would be useful to write down my thoughts about these notes. Of ...
    Posted to Microsoft OLAP by Mosha Pasumansky (Weblog) by mosha on June 2, 2007
  • Best practices for server ADOMD.NET stored procedures

    In this article we will discuss some of the best practices around writing efficient Analysis Services stored procedures using server ADOMD.NET. These days there is plenty of information about writing efficient MDX - in books, whitepapers, blogs, forums etc. Just recently Microsoft released two documents - Performance Guide and Design Best ...
    Posted to Microsoft OLAP by Mosha Pasumansky (Weblog) by mosha on April 19, 2007
  • Averages, ratios, division by zero and NON_EMPTY_BEHAVIOR

    How to get averages and other ratio based MDX calculations demonstrate great performance ? I thought I covered this subject in great depth before, but I probably wasn't concise enough. Last week I was asked to help with performance to very big and important customer (who shall remain unnamed). When I arrived on site, I found the project staff to ...
    Posted to Microsoft OLAP by Mosha Pasumansky (Weblog) by mosha on March 6, 2007
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