Re: description of Aggregate Expressions

John Lumby <johnlumby(at)hotmail(dot)com> writes:
> On 12/05/19 18:06, David G. Johnston wrote:
>> Then I would have to say the proposed solution to this edge case is worse than the problem. I also don't expect there to be a clean solution to dealing with the complexities of expressions at the syntax diagram level.

> Yes, I see what I suggested is not ideal either. But I think something needs to be changed.

> How about replacing "expression [ , ... ]" by "parameter_list" in the description, and then stating that parameter_list can be either a single expression or , if the particular aggregate function accepts it (for which, consult that function's reference), a comma-separated list of expressions.

That's just as wrong. As we tried to explain before, the
parenthesized-list syntax is a row constructor, so it only works
in cases where the aggregate function can accept a composite
argument type. Most don't.

Moreover, the very same thing holds in *any* expression context,
not only aggregate arguments. So if we took this seriously there
would have to be a lot of other places plastered with equally
confusing/unhelpful addenda.

regards, tom lane