ALLSELECTED Shadow Filters

Hi ahmeddaffaie80 ,

It's great that you are reading "The Definitive Guide to DAX" by Russo and Ferrari. They are experts in the field and their book is a great resource for learning DAX.

Regarding your question about ALLSELECTED, it is true that the SUMMARIZECOLUMNS function creates a filter context that overrides any incoming filter context later. This means that if you select a few values from a slicer, this context will be of high priority and will override any incoming filter context later.

However, the behavior of ALLSELECTED can be affected by other factors, such as shadow filters or special cases. It is possible that the book is referring to these factors when explaining the execution plan.

Regarding your observation about CALCULATETABLE, it is correct that the result of CALCULATETABLE depends on the expressions in A and B. If any expression contains an ALL* function, it will be dominant over the other expressions. If A and B are from different columns or tables, the result is the intersection between them.

Best Regards,

Stephen Tao

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.