Re: BUG #19353: Error XX000 if referencing expanded array in grouping set: variable not found in subplan target list

On Mon, Dec 15, 2025 at 11:28 PM Richard Guo <guofenglinux@gmail.com> wrote:
> To fix, I think we should ignore the grouping nulling bit when
> checking if an expression from the grouping target is available in the
> pre-grouping input target.  This is actually what we do in setrefs.c.
>
> Hence, attached patch.

Regarding back-patching, we need to pass a new parameter to
split_pathtarget_at_srfs() to indicate whether we are processing a
grouping target.  But doing that would break ABI compatibility.

To avoid this, I refactored the logic into a new static workhorse
function which accepts the new parameter.  The original
split_pathtarget_at_srfs() is preserved as a wrapper that calls this
static function.  I believe this is ABI safe.

The patch also introduces a new extern function that calls the
workhorse with the grouping flag enabled.  Additionally, it adds two
new fields to struct split_pathtarget_context, but that struct is
defined entirely within the .c file.

Could someone confirm if this is ABI safe?  I don't want to cause ABI
troubles in back branches.

- Richard