Re: [PATCH] Fix wrong comment in JsonTablePlanJoinNextRow() - Mailing list pgsql-hackers

Hi,

On Thu, Apr 16, 2026 at 11:05 AM Chao Li <li.evan.chao@gmail.com> wrote:
> > On Apr 15, 2026, at 16:28, 胡传文 <463945512@qq.com> wrote:
> >
> > Hi,
> > Found a misleading comment in JsonTablePlanJoinNextRow() while reading
> > the JSON_TABLE execution code.
> > The function returns false when both siblings are exhausted (meaning no
> > more rows), but the comment says "there are more rows" — the exact
> > opposite of what's happening. The code itself is correct.
> > if (!JsonTablePlanNextRow(planstate->right))
> > {
> > /* Right sibling ran out of row, so there are more rows. */ /* wrong */
> > return false;
> > }
> > A reader might reasonably treat this as a bug and flip the return value,
> > which would cause JSON_TABLE UNION plans to loop indefinitely.
> > Patch attached.

Thanks for the report and the patch.

> The fix looks correct to me. I guess “no” was just unintentionally missed.
>
> A small comment, I just feel “too” you newly added might not be needed.

Actually, I'd keep it, because it ties the comment to the left-sibling
check just above.

Will push the attached down to v17.

--
Thanks, Amit Langote