Erik Darling looks the gift horse in the mouth:
Quite a while back, I blogged about how much I’d love to have this as a function. We… sort of got it. It doesn’t do dates natively, but you can work around some of that with date functions.
In this post, I want to go over some of the disappointing performance issues I found when testing this function out.
It’s not good news but it’s important to understand if you’re planning to use this when SQL Server 2022 comes out. Also, the things Erik mentions are easier to fix (potentially) than modifications in the signature of a function, as they’re internal. I wouldn’t guarantee that things will certainly be better but there are some good cases when we saw performance improvements between early CTPs and RTM.