Re: CALL versus procedures with output-only arguments

čt 20. 5. 2021 v 19:53 odesílatel Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> napsal:

> I'm not too happy with this:
>
> regression=# create procedure p1(out x int) language plpgsql
> regression-# as 'begin x := 42; end';
> CREATE PROCEDURE
>
> regression=# call p1();
> ERROR: procedure p1() does not exist
> LINE 1: call p1();
> ^
> HINT: No procedure matches the given name and argument types. You might
> need to add explicit type casts.
>
> regression=# call p1(null);
> x
> ----
> 42
> (1 row)
>
> I can see that that makes some sense within plpgsql, where the CALL
> ought to provide a plpgsql variable for each OUT argument. But it
> seems moderately insane for calls from SQL. It certainly fails
> to match the documentation [1], which says fairly explicitly that
> the argument list items match the *input* arguments of the procedure,
> and further notes that plpgsql handles output arguments differently.
>
> I think we ought to fix this so that OUT-only arguments are ignored
> when calling from SQL not plpgsql. This is less than simple, since
> the parser doesn't actually have any context that would let it know
> which one we're doing, but I think we could hack that up somehow.
> (The RawParseMode mechanism seems like one way we could pass the
> info, and there are probably others.)
>

+1

Pavel

> Alternatively, if we're going to stick with this behavior, we have
> to change the docs to explain it. Either way it seems like an
> open item for v14. (For those who've forgotten, OUT-only procedure
> arguments are a new thing in v14.)
>
> regards, tom lane
>
> [1] https://www.postgresql.org/docs/devel/sql-call.html
>
>
>