If you have a Slowly Changing Dimension (SCD) Type 2 for your customer and you want to calculate the number of distinct customers that bought a product, you cannot use the simple formula: Customers := DISTINCTCOUNT( FactTable[Customer Id] ) ) because it would return the number of distinct versions of customers. What you really want to do is to ...

The SQL Server Profiler provides you many information regarding the internal behavior of DAX queries sent to a BISM Tabular model. Similar to MDX, also in DAX there is a Formula Engine (FE) and a Storage Engine (SE). The SE is usually handled by Vertipaq (unless you are using DirectQuery mode) and Vertipaq SE Query classes of events gives you a ...

In September 2006 I had announced in this blog the release of the first version of The Many-to-Many Revolution, a whitepaper that describes how to leverage the many-to-many dimension relationships feature that had being available since Analysis Services 2005. The paper contains many generic patterns that can be applied in many common data ...

The Analysis Services team just posted a blog entry with a few useful links to jumpstart your experience with Tabular project in Analysis Services ''Denali''. In these early days I read several messages asking for clarification about the names and acronyms used in Denali. For a complete description I suggest you to read the Analysis Services - ...

I and Alberto Ferrari will present a DAX Deep Dive training day at SQLBits 9 in Liverpool, on September 29th. The conference will continue on September 30th and October 1st. Registrations are not yet open, but you should definitely save the date for SQLBits! The goal of our session will be to cover all of the aspects of DAX, starting from the ...

During TechEd 2011, Microsoft announced an important update to its BI roadmap. The reason why this is important is related to the previous announcement, which I discussed in November 2010 by including links to several sources and comments. At PASS Summit 2010 the announcement regarding the next version of SQL Server, codenamed ''Denali'', ...

In the last months I talked mostly about PowerPivot, but Analysis Services is still growing and a very good sign of that is the number of downloads of The Many-to-Many Revolution whitepaper, who has been published almost 5 years ago and recently surpassed 20,000 downloads. The download trend is a constant line made of tens of downloads every ...

Jeffrey Wang wrote a very detailed blog post about recursive calculations in MDX with Analysis Services. In these days I'm doing some comparison between DAX and MDX (well, between Vertipaq/PowerPivot and OLAP/SSAS engines) and I'm discovering that MDX calculation engine is much more smart than you might think in certain conditions. I cannot ...

Microsoft recently announced a new roadmap for its BI architecture. The next version of SQL Server, codenamed “Denali”, is going to introduce a new semantic model named BISM (Business Intelligence Semantic Model). Analysis Services will host it and it will be queryable through MDX and DAX. DAX has been introduced in PowerPivot as an expression ...