Re: pg_dump crash due to incomplete ordering of DO_SUBSCRIPTION_REL objects

On Wed, 17 Dec 2025 at 00:54, Noah Misch <noah@leadboat.com> wrote:
>
> On Tue, Dec 16, 2025 at 05:22:36PM +0530, vignesh C wrote:
> > On Tue, 16 Dec 2025 at 00:00, Noah Misch <noah@leadboat.com> wrote:
> > > On Mon, Dec 15, 2025 at 11:35:35PM +0530, vignesh C wrote:
> > > > This issue has started failing after commit:
> > > > commit 0decd5e89db9f5edb9b27351082f0d74aae7a9b6
> > > > Sort dump objects independent of OIDs, for the 7 holdout object types.
>
> > > That makes sense.  Thanks.  Do you have commands we could add to
> > > src/test/regress/sql/subscription.sql to cover this code?
> >
> > This dumping of subscription relation is specific to upgrading to
> > preserve the subscription relation. So I felt we will not be able to
> > add tests to subscription.sql, instead how about adding one more table
> > to 004_subscription.pl where subscription upgrade tests are verified
> > like the attached patch.
>
> That's a good way to test it.
>
> > --- a/src/bin/pg_dump/pg_dump_sort.c
> > +++ b/src/bin/pg_dump/pg_dump_sort.c
> > @@ -454,6 +454,20 @@ DOTypeNameCompare(const void *p1, const void *p2)
> >               if (cmpval != 0)
> >                       return cmpval;
> >       }
> > +     else if (obj1->objType == DO_SUBSCRIPTION_REL)
> > +     {
> > +             SubRelInfo *srobj1 = *(SubRelInfo *const *) p1;
> > +             SubRelInfo *srobj2 = *(SubRelInfo *const *) p2;
> > +
> > +             /* Sort by schema name (subscription name was already considered) */
>
> Let's change the values getSubscriptionRelations() stores in
> SubrRelInfo.obj.namespace and SubrRelInfo.obj.name to be more like
> DO_PUBLICATION_REL:
>
>                 pubrinfo[j].dobj.namespace = tbinfo->dobj.namespace;
>                 pubrinfo[j].dobj.name = tbinfo->dobj.name;
>                 pubrinfo[j].publication = pubinfo;
>
> DO_SUBSCRIPTION_REL (new in v17) is gratuitously different:
>
>                 subrinfo[i].dobj.name = pg_strdup(subinfo->dobj.name);
>                 subrinfo[i].tblinfo = tblinfo;
>                 subrinfo[i].subinfo = subinfo;

Modified

> What do you think?  This would change sort order from (subname, rel) to (rel,
> subname).  Historically, we've avoided churning dump order, in case folks diff
> dump output over time.

Although grouping by publication and subscription would be cleaner,
publication relations have been ordered first by relation and then by
publication. Retaining the same ordering for subscription relations
preserves consistency.

> I bet that practice is less common for binary dumps.
> Since DO_SUBSCRIPTION_REL is only for binary dumps, let's just change it.
>
> > +             cmpval = strcmp(srobj1->tblinfo->dobj.namespace->dobj.name,
> > +                                             srobj2->tblinfo->dobj.namespace->dobj.name);
>
> The subrinfo change will make this comparison go away.  If it had stayed, it
> should be ready for namespace==NULL like pgTypeNameCompare() is.  (I think
> pgTypeNameCompare() could drop that defense, because the getTypes() call to
> findNamespace() will pg_fatal() on absence.  Until it does drop that defense,
> the rest of pg_dump_sort.c should handle namespace==NULL.)
>
> > --- a/src/bin/pg_upgrade/t/004_subscription.pl
> > +++ b/src/bin/pg_upgrade/t/004_subscription.pl
>
> > -# Wait till the table tab_upgraded1 reaches 'ready' state
> > +# Wait till the tables tab_upgraded and tab_upgraded1 reaches 'ready' state
>
> s/reaches/reach/ there.

Modified

> To find other text needing edits, I searched this file for tab_upgraded.  The
> following comment still implies "all tables" encompasses just two:
>
> # ------------------------------------------------------
> # Check that pg_upgrade is successful when all tables are in ready or in
> # init state (tab_upgraded1 table is in ready state and tab_upgraded2 table is
> # in init state) along with retaining the replication origin's remote lsn,
> # subscription's running status, failover option, and retain_dead_tuples
> # option.
> # ------------------------------------------------------

Updated the comments

The attached v3 version patch has the changes for the same.

Regards,
Vignesh