Hi, On 2019-10-22 15:06:50 -0400, Tom Lane wrote: > Andres Freund <and...@anarazel.de> writes: > > On 2019-10-20 10:27:19 -0400, Tom Lane wrote: > >> "RETURNS NOT NULL", perhaps? That'd have the advantage of not requiring > >> any new keyword. > > > That could work. > > Actually, I think we probably don't need any SQL representation of this > at all, because if what you're going to do with it is omit logically > necessary null-value checks, then a wrong setting would trivially crash > the server. Therefore, we can never give the ability to set this flag > to users; we could only set it on built-in functions.
I assumed we'd allow it plainly for C functions, as there's already myriad ways to break the server. And for anything but C, we probably should check it in the language handler (or some generic code invoking that). I think it's interesting to have this function property not just for performance, but also semantic reasons. But it's fine to include the check in the function handler (or some wrapper around those, if we think that's worthwhile), rather than relying on the function to get this right. > This doesn't seem too awful to me, because non-builtin functions are > most likely slow enough that it doesn't matter. With builtin, do you mean just internal functions, or also "C"? I think it's worthwhile to allow "C" directly if benchmarks proves this is worthwhile. Greetings, Andres Freund
