Re: Bug: wrong relname in RemoveSubscriptionRel() error detail

On Mon, Mar 30, 2026 at 1:44 PM Zhijie Hou (Fujitsu)
<houzj(dot)fnst(at)fujitsu(dot)com> wrote:
>
> On Monday, March 30, 2026 2:33 PM Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com> wrote:
> > > On Mar 30, 2026, at 14:16, Nisha Moond <nisha(dot)moond412(at)gmail(dot)com>
> > wrote:
> > >
> > > On Fri, Mar 27, 2026 at 3:22 PM Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com> wrote:
> > > > This looks like a first-day bug introducing by ce0fdbf, so I think it’s worth
> > > > back-patching.
> > > >
> > > I tried reproducing the said bug on HEAD, but it doesn’t seem to exist
> > > in the current code.
> > >
> > > To hit the mentioned error, the subid has to be invalid -
> > > if (!OidIsValid(subid) && <==
> > > And currently, the only path that uses an invalid subid is via
> > > heap_drop_with_catalog() :
> > > …
> > > /*
> > > * Remove any associated relation synchronization states.
> > > */
> > > RemoveSubscriptionRel(InvalidOid, relid);
> > > …
> > >
> > > But here relid is always a valid OID (it's the table being dropped).
> > > The corresponding pg_class row is deleted after
> > > RemoveSubscriptionRel(), i.e. via a later call to
> > > DeleteRelationTuple(relid);
> > >
> > > It can only happen with a hypothetical future caller of
> > > RemoveSubscriptionRel(InvalidOid, InvalidOid). And in that case, using
> > > "subrel->srrelid" would be correct.
> > >
> > > So this doesn’t appear to be a real issue in the current code, and
> > > doesn’t look like a bug to fix now. IMO, if such a caller is added in
> > > the future, we can add a guard at that point.
> > >
> > > --
> > > Thanks,
> > > Nisha
> >
> > Hi Nisha,
> >
> > Thanks for your review.
> >
> > I think one current call site may have been overlooked. In DropSubscription(),
> > we have:
> > ```
> > /* Remove any associated relation synchronization states. */
> > RemoveSubscriptionRel(subid, InvalidOid);
> > ```
>
> This won't trigger the bug either, since it passes a valid subscription OID to
> the function, while the function only reports an error when an invalid OID is
> passed.
>
> >
> > I agree this is an edge-case bug and may be difficult to reproduce in practice.
> > But from the function’s semantics, it seems clear to me that the wrong
> > relation OID is used in the error detail, regardless of how easy it is to trigger
> > today.
>
> Since this is a public function, I think it should be OK to fix it as it's good
> to make the function future-proof anyway.
>

Even if it is exposed, it is not clear to me in which case one would
like to use it the way it can lead to a problem. I feel unless we have
some concrete case it may not be beneficial to change it.

--
With Regards,
Amit Kapila.