22-25 April 2026 
SQLBits 2024
Understanding window functions in DAX
Introduction to DAX window functions and apply semantics through several examples to understand their capabilities and performance.
Window functions (INDEX, OFFSET, WINDOW, RANK, and ROWNUMBER) are the latest additions to the DAX language; they also introduce a new concept named apply semantics. They are extremely powerful in simplifying writing DAX code that needs to work on sorted tables while sometimes (but not always) increasing performance for several calculations, like running totals, comparing one row with the previous one, etc.
In this session, we introduce window functions and apply semantics through several examples to understand their capabilities and performance.
In this session, we introduce window functions and apply semantics through several examples to understand their capabilities and performance.
Speakers
Marco Russo's previous sessions
Advanced DAX
Unleash the full power of evaluation context manipulation, learn about expanded tables, control the data lineage, avoid circular dependencies, and manage relationships at different granularities.
Aggregations in Power BI
Introduce Power BI aggregations with practical examples, evaluate pros and cons, and learn how to use alternative approaches by using DAX to control the aggregation used.
Using ALLEXCEPT or ALL/VALUES?
Learn when to use ALL / VALUES instead of ALLEXCEPT in DAX calculations.
Understanding window functions in DAX
Introduction to DAX window functions and apply semantics through several examples to understand their capabilities and performance.