Forum Discussion
Power Query M or DAX
Hi tlotfi
Power query is better for model data (clean, transform etc.) but DAX is better for calculations (specially for measures which don't take a lot of ram when you’re doing massive computations).
Good thread to go through.
https://community.powerbi.com/t5/Desktop/Dax-or-M-Language/td-p/136827
I would say that if it can be done in PowerQuery, that's where you should do it so that you don't slow down PowerBI after the data is loaded. For example, if you're creating another column, it's best to do that in PowerQuery as once it's done, it's done. If you do a calculated column in DAX, then everytime you apply a filter, cross-filter, or whatever, the calculated column get re-calculated.
I would say that if it can be done in PowerQuery, that's where you should do it so that you don't slow down PowerBI after the data is loaded. For example, if you're creating another column, it's best to do that in PowerQuery as once it's done, it's done. If you do a calculated column in DAX, then everytime you apply a filter, cross-filter, or whatever, the calculated column get re-calculated.