DAX Archives - Phil Seamark on DAX

The Impact of Primary Keys on DAX Query Performance in Power BI

November 14, 2025November 15, 20251 Comment

When writing DAX queries, performance tuning often comes down to small design decisions that have big consequences. One such decision is whether to include Primary Key columns from Dimension tables in your SUMMARIZECOLUMNS statements. This is particularly important when those Dimension tables use DUAL or IMPORT storage modes. This article explains why doing so can … Continue reading The Impact of Primary Keys on DAX Query Performance in Power BI

How to Generate a DAXX File for Performance Tuning

October 31, 2025October 31, 20251 Comment

When troubleshooting slow DAX queries, sharing the right diagnostic information with an expert can make all the difference. That’s where a DAXX file comes in. This special file format is created using DAX Studio. It bundles essential metadata and performance details without exposing query results. It’s perfect for collaborative optimisation. What is a DAXX File? … Continue reading How to Generate a DAXX File for Performance Tuning

DAX Pareto Calculation

April 17, 2023December 5, 202310 Comments

I always enjoy it when we get new DAX functions, especially so for the new set of WINDOW Functions recently added. As part of the April 2023 release of Power BI Desktop, we now have a RANK function and the ability to use a measure to control the order within the existing WINDOW function. The … Continue reading DAX Pareto Calculation

DAX : Count number of last known state

May 17, 2021May 17, 20216 Comments

Using DAX to help group and count the last known state I got asked recently to help with a DAX measure for an interesting problem in the inventory domain. The requirement is to generate a chart showing the count of the last known State of a given number of items. Here is a walkthrough of … Continue reading DAX : Count number of last known state