Re: Assert single row returning SQL-standard functions

so 30. 8. 2025 v 9:46 odesílatel Joel Jacobson <joel(at)compiler(dot)org> napsal:

> On Fri, Aug 29, 2025, at 22:42, David G. Johnston wrote:
> > I think the file location is fine but have an idea for where within the
> > file to place this: or rather a minor re-working of these so three
> > variants that do the same test aren't spread across the whole page.
> >
> ...docs diff...
>
> I like the idea of merging "IS NULL" with "ISNULL" and "IS NOT NULL"
> with "NOTNULL", to make it clear they are the same thing but with
> standard/non-standard syntax.
>
> Not so sure about moving nonnull() from Table 9.3. Comparison Functions
> up to Table 9.2. Comparison Predicates, since it's a function, so 9.3
> feels more suitable.
>
> > I do have a concern regarding its treatment of composites/row-valued
> > inputs (i.e. is this considered IS NOT NULL or IS DISTINCT FROM NULL)
>
> I think the semantics for the new function should be to error-on-null,
> where the input strictly needs to be NULL to get an error, since then
> it's possible to use such function for the assert single row use-case
> even for functions that returns table / setof.
>
> I do share your concern due to the current naming of the function
> though.
>
> How about renaming it to error_on_null(anyelement) -> anyelement
> instead?
>

+1

Pavel

>
> That way, we avoid the ambiguity coming from what "nonnull" would mean,
> since it's only NULL that IS NULL.
>
> > The subject of this thread also is only tangentially related to the
> patch now.
>
> Yeah, I think we should start a new thread for the patch, but holding onto
> that until we've worked out what the function should be named and
> what semantics we think it should have.
>
> /Joel
>