Date: Fri, 29 Sep 2023 14:26:19 -0400
From: Bruce Momjian <bruce@momjian.us>
To: James Coleman <jtc331@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>,
	pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Fix incorrect comment reference
Message-ID: <ZRcWyyytlXXvzV7e@momjian.us>
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Precedence: bulk

On Mon, Jan 23, 2023 at 06:42:45PM -0500, James Coleman wrote:
> On Mon, Jan 23, 2023 at 4:07 PM James Coleman <jtc331@gmail.com> wrote:
> >
> > 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.
> 
> Updated patch attached.

Patch applied.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Only you can decide what is important to you.