Ah, Sergiy... my ol' friend. Long time no see. Thank you for stopping by and thanks for the great explanations.

Yeah... I agree... most folks using front end code aren't going to notice any difference between using a Scalar UDF or an iTVF. Chances are, many won't even be able to measure the differences because of the extremely low rowcounts especially since I showed them why not to use SET STATISTICS to measure Scalar UDF performance.

I do try to avoid Scalar UDFs, though, because most of the stuff I do is on staging tables where the cumulative times of multiple functions across many columns does start to make a difference especially when loading hundreds of large files in such a manner. 5% performance differences can really start to stack up in batch code.

For GUI code, I write it as if it were large volume batch code because so many people will "leverage" any code they can find in a schedule pinch for their own batch code. If the iTVFs turn out to be a bit more complicated than some will understand, a well placed comment here and there in the code takes care of the problem. If not, then they probably shouldn't be trying to modify the code to begin with. 🙂

Of course, it's still possible to write crap code in an iTVF. iTVFs aren't a panancea.