Window functions - when to use?

[iBusinessBI]

I've seen several articles with examples of how to use the new Window functions.

But I am confused. From what I saw, the same result can be achieved with regular time intelligent or other functions. 

So when do we HAVE to use them?

And when is it RECOMMENDED to use them as a general advice?

[TomMartens]

Hey @iBusinessBI ,

to be honest, currently there is no general answer, the reason for this is quite simple: the development of the new window functions (INDEX, OFFSET, and WINDOW) is not done yet. I expect that over the next releases, further enhancements are happening.

Nevertheless, the new functions bring a lot of performance improvements for this reason I started out to replace "previous" patterns with "new" patterns. If challenged with the "Previous value" task I started to use OFFSET: Unlock an ample new world by seeing through a window - Mincing Data - Gain Insight from Data (minced... instead of my old pattern: The previous value - Mincing Data - Gain Insight from Data (minceddata.info)

For now, I recommend explore the new functions if you have time, if your current patterns are performing well there is no need to change behavior, at least not for now.

I was considering replacing RANX, but I realized that RANKX is faster than the new functions, this means the window functions are versatile but are not here to replace everything.

Hopefully, this helps a little to wonder the plains of DAX.

Regards,

Tom