Re: BUG #17803: Rule "ALSO INSERT ... SELECT ..." fails to substitute default values

On Tue, 21 Feb 2023 at 15:05, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> It seems like this bit:
>
> + rtr = (RangeTblRef *) linitial(pt->jointree->fromlist);
> + selectrte = rt_fetch(rtr->rtindex, pt->rtable);
> + selectquery = selectrte->subquery;
>
> is missing several essential checks. Is the node extracted from
> jointree->fromlist actually a RangeTblRef? Seems like it could
> be a JoinExpr or FromExpr instead; even if it can't be that today,
> an IsA check is cheap future-proofing. Likewise, once you've
> got your hands on the RTE, you should check rtekind == RTE_SUBQUERY
> rather than assuming it's safe to touch the subquery field.
>
> (I see that getInsertSelectQuery isn't much better about this,
> but we should fix that while we're at it.)
>

Yeah, that makes sense. Something like this? (I think an elog() is
probably more useful than an Assert(), if we don't find what we
expect.)

Regards,
Dean