Re: BUG #19631: currtid2() on a view with GROUP BY ctid crashes with XX000

Hi,

On Wed, 19 Aug 2026 at 14:54, PG Bug reporting form <noreply(at)postgresql(dot)org>
wrote:

> The following bug has been logged on the website:
>
> Bug reference: 19631
> Logged by: Zheng Hacker
> Email address: hackerzheng666(at)gmail(dot)com
> PostgreSQL version: 19beta3
> Operating system: Linux x86_64
> Description:
>
> PostgreSQL version: 20devel (commit bdbf662, 2026-08-19)
> OS: Linux x86_64
>
> Calling currtid2() on a view whose SELECT includes ctid in a GROUP BY
> hits elog(ERROR) without errcode() in tid.c, producing SQLSTATE XX000.
>
> Reproducer:
>
> CREATE TABLE tid_tab (a int);
> INSERT INTO tid_tab VALUES (1);
> CREATE VIEW tid_view_with_ctid AS
> SELECT ctid, a FROM tid_tab GROUP BY ctid, a;
> SELECT currtid2('tid_view_with_ctid'::text, '(0,1)'::tid);
> -- ERROR: XX000: currtid cannot handle this view
> -- LOCATION: currtid_for_view, tid.c:435
>
> Note: the view has a ctid column (so it passes the tididx check at
> line 389 which does have a proper errcode), but the GROUP BY prevents
> the code from resolving the TLE to a simple base-table Var, so it
> falls through to the elog(ERROR) at line 435 which lacks errcode().
>
> Expected: a proper SQLSTATE (e.g. 0A000 feature_not_supported).
>
> Found by automated SQL fuzzing.
> Credit: Zheng Wang, Yanjie Zhao, Yiyang Liu
>

Thanks for the reports. #19629, #19630 and #19631 share one cause: an
error ordinary SQL can reach is raised without an errcode(), so the user
sees XX000.

I scanned the backend for the same pattern, and the attached patch fixes
those three plus four more sites with the same problem: unicode_assigned()
on a non-UTF8 encoding, the pg_control_*() CRC check, a GiST tuple marked
invalid, and ALTER COLLATION ... REFRESH VERSION on "default".

Regards,
Ayush