Expanded tables are the core of DAX; understanding how they work is of paramount importance. This article provides a theoretical foundation of what expanded tables are, along with fundamental concepts useful when reading DAX code.  Read more

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

This article describes the differences between report-based tools and model-based tools. Because Power BI is a model-based tool and not a report-based tool, it is useful to have a quick reference guide explaining these differences.  Read more