[PATCH] Fix wrong comment in JsonTablePlanJoinNextRow()

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.
Regards,
Chuanwen Hu<fix-jsontable-comment.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.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/

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

On Thu, Apr 16, 2026 at 12:03 PM Amit Langote <amitlangote09@gmail.com> wrote:

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.

Done.

--
Thanks, Amit Langote