Re: Wrong results from join removal with DISTINCT ON + SRF subquery

On Sat, Aug 22, 2026 at 10:15 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> > Attached is a patch to not rely on DISTINCT ON for distinctness if
> > there are any tlist SRFs. This is more conservative than necessary,
> > since the SRFs are only postponed when there is an ORDER BY and none
> > of them is in a sort/group column, but I don't think it's worth
> > duplicating that logic in analyzejoins.c.

> I didn't study the patch in any detail, but I concur with your
> thinking here. SRFs in the tlist are kind of a legacy usage in the
> first place, so I don't feel a need to expend lots of effort on
> optimizing cases like this.

Thanks for looking at this! I'll push the patch and back-patch to all
supported branches if there are no objections.

- Richard