Re: remaining sql/json patches

On Thu, Mar 7, 2024 at 23:14 Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:

> On 2024-Mar-07, Tomas Vondra wrote:
>
> > I was experimenting with the v42 patches, and I think the handling of ON
> > EMPTY / ON ERROR clauses may need some improvement.
>
> Well, the 2023 standard says things like
>
> <JSON value function> ::=
> JSON_VALUE <left paren>
> <JSON API common syntax>
> [ <JSON returning clause> ]
> [ <JSON value empty behavior> ON EMPTY ]
> [ <JSON value error behavior> ON ERROR ]
> <right paren>
>
> which implies that if you specify it the other way around, it's a syntax
> error.
>
> > I'm not sure what the SQL standard says about this, but it seems other
> > databases don't agree on the order. Is there a particular reason to
> > not allow both orderings?
>
> I vaguely recall that trying to also support the other ordering leads to
> having more rules.

Yeah, I think that was it. At one point, I removed rules supporting syntax
that wasn’t documented.

Now maybe we do want that because of compatibility
> with other DBMSs, but frankly at this stage I wouldn't bother.

+1.

>