I and Alberto Ferrari will speak at SQLBits XI (Nottingham, UK – May 2-4, 2013) and there are many good reasons to join us there, especially if you are interested to DAX! Here are our sessions: Thursday, 02 May 2013 – Training Day - From 0 to DAX The entire day is dedicated to learning DAX, starting from the syntax and going forward ...

After the first two editions of the SSAS Tabular Workshop, I and Alberto had some time to flush some of the pending activities. We published two articles: Clever Hierarchy Handling in DAX: DAX is not a hierarchy-friendly language, especially if you have a MDX background. If you have to implement hierarchy-based calculation, MDX is still ...

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 ...

Analysis Services answers to query in MDX, in DAX (by now just for Tabular models) and has a limited capability to answer SQL queries. It is not useful for any development or client tool, but I wanted to write a blog post on it in order to be able to retrieve these information I gathered during study of DAX and MDX queries sent to Tabular ...

A few weeks ago I received a question that inspired me in writing this article about how to handle data at different granularities in PowerPivot and BISM Tabular. I think this is a common pattern when you have a budget table that contains data at an aggregated level (like month and product category) and you want to compare it with sales that are ...

I wrote a short article about query projection in DAX. To make the story short, you should always use SUMMARIZE in order to remove columns from a table in a query. Thus, if you just want three columns from a table, instead of writing this in SQL: SELECT Col1, Col2, Col3 FROM Table you should write this in DAX: EVALUATE SUMMARIZE( Table, ...

You should have already read that DAX is simpler than MDX. It’s true, and sometime you have to pay a price for simplicity. I am used to say that DAX is somewhere between SQL and MDX. In fact, SQL requires you to put any relationship in the query (using JOIN or subqueries) whereas MDX can only leverage on existing relationships in the underlying ...

The video of the session Vertipaq vs OLAP: Change Your Data Modeling Approach that I delivered at SQLBits 9 is finally available! You can find here the video of sessions I and Alberto Ferrari delivered at the last two SQLBits. Last week we also submitted some proposals for SQLBits 10 in London, which will be a big SQLbits edition. Here is the ...

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 ...