Window functions (like INDEX, OFFSET, WINDOW, and others) are one of the latest addition to DAX. These functions introduce a new concept named "apply semantics".

Window functions are extremely powerful in simplifying DAX code that needs to work on sorted tables while also increasing performance for several calculations, like running totals, comparing one row with the previous one, etc.

In this session, we introduce window functions and the "apply semantics" through several examples to understand their capabilities and performance.