ALLSELECTED is a powerful function that can hide several traps. This article is an in-depth analysis of the behavior of ALLSELECTED, explaining shadow filter contexts, what they are and how they are used by ALLSELECTED.  Read more

This article describes how to use variables to optimize the performance of DAX expressions containing multiple instances of the same measure or the same sub-expression.  Read more

This article explains how the context transition interacts with the filter arguments of a CALCULATE function in DAX. This is important in order to avoid unexpected results with complex calculations made in filter arguments.  Read more

We are approaching the end of 2017, so it is a good time to review what happened in the DAX world this year, what we’ve been up to at SQLBI and what is going to happen in 2018. New DAX…  Read more

This article shows a technique in DAX to compute the sales volume of products that were available right from the beginning of a selected time period, ignoring products introduced afterwards.  Read more

This article describes a counterintuitive behavior of BLANK in DAX measures affecting Power BI, Analysis Services, and Power Pivot. That behavior could cause mistakes in a report using alternate expressions of the same calculation. Indeed, these expressions are not equivalent…  Read more

This article describes how to extract raw data stored in the Tabular engine, used by Analysis Service Tabular, Power BI, and Power Pivot.  Read more

The Detail Rows Expression in a Tabular model provides the user with control over the drillthrough results obtained by showing details of a measure. This article describes typical DAX expressions you can use in this property.  Read more

DAX Studio is a tool to write, execute, and analyze DAX queries in Power BI Designer, Power Pivot for Excel, and Analysis Services Tabular. It includes an Object Browser, query editing and execution, formula and measure editing, syntax highlighting and…  Free download

VertiPaq Analyzer is useful to analyze VertiPaq storage structures for a data model in Analysis Services Tabular. A complete description and short tutorial is available in the article Data Model Size with VertiPaq Analyzer.  Free download