On Mon, Jan 23, 2023 at 3:41 PM Robert Haas <robertmhaas@gmail.com> wrote:
>
> On Mon, Jan 23, 2023 at 3:19 PM James Coleman <jtc331@gmail.com> wrote:
> > On Mon, Jan 23, 2023 at 1:26 PM Robert Haas <robertmhaas@gmail.com> wrote:
> > > On Mon, Jan 23, 2023 at 8:31 AM James Coleman <jtc331@gmail.com> wrote:
> > > > See the attached for a simple comment fix -- the referenced
> > > > generate_useful_gather_paths call isn't in grouping_planner it's in
> > > > apply_scanjoin_target_to_paths.
> > >
> > > The intended reading of the comment is not clear. Is it telling you to
> > > look at grouping_planner because that's where we
> > > generate_useful_gather_paths, or is it telling you to look there to
> > > see how we get the final target list together? If it's the former,
> > > then your fix is correct. If the latter, it's fine as it is.
> > >
> > > The real answer is probably that some years ago both things happened
> > > in that function. We've moved on from there, but I'm still not sure
> > > what the most useful phrasing of the comment is.
> >
> > Yeah, almost certainly, and the comments just didn't keep up.
> >
> > Would you prefer something that notes both that the broader concern is
> > happening via the grouping_planner() stage but still points to the
> > proper callsite (so that people don't go looking for that confused)?
>
> I don't really have a strong view on what the best thing to do is. I
> was just pointing out that the comment might not be quite so obviously
> wrong as you were supposing.
"Wrong" is certainly too strong; my apologies.
I'm really just hoping to improve it for future readers to save them
some confusion I had initially reading it.
James Coleman