Re: long-standing data loss bug in initial sync of logical replication

On Tue, Jul 9, 2024 at 8:14 PM vignesh C <vignesh21(at)gmail(dot)com> wrote:
>
> On Tue, 9 Jul 2024 at 17:05, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > On Mon, Jul 1, 2024 at 10:51 AM vignesh C <vignesh21(at)gmail(dot)com> wrote:
> > >
> > >
> > > This issue is present in all supported versions. I was able to
> > > reproduce it using the steps recommended by Andres and Tomas's
> > > scripts. I also conducted a small test through TAP tests to verify the
> > > problem. Attached is the alternate_lock_HEAD.patch, which includes the
> > > lock modification(Tomas's change) and the TAP test.
> > >
> >
> > @@ -1568,7 +1568,7 @@ OpenTableList(List *tables)
> > /* Allow query cancel in case this takes a long time */
> > CHECK_FOR_INTERRUPTS();
> >
> > - rel = table_openrv(t->relation, ShareUpdateExclusiveLock);
> > + rel = table_openrv(t->relation, ShareRowExclusiveLock);
> >
> > The comment just above this code ("Open, share-lock, and check all the
> > explicitly-specified relations") needs modification. It would be
> > better to explain the reason of why we would need SRE lock here.
>
> Updated comments for the same.
>

The patch missed to use the ShareRowExclusiveLock for partitions, see
attached. I haven't tested it but they should also face the same
problem. Apart from that, I have changed the comments in a few places
in the patch.

--
With Regards,
Amit Kapila.