Re: logical replication seems broken

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: vignesh C <vignesh21(at)gmail(dot)com>
Cc: Erik Rijkers <er(at)xs4all(dot)nl>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: logical replication seems broken
Date: 2021-02-16 03:37:21
Message-ID: CAA4eK1LjP=-qNhOzhBNrujwKbcL8c4sdnPGGJn3+e33SedQVhg@mail.gmail.com
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On Mon, Feb 15, 2021 at 7:50 PM vignesh C <vignesh21(at)gmail(dot)com> wrote:
>
> On Mon, Feb 15, 2021 at 6:14 PM <er(at)xs4all(dot)nl> wrote:
> >
> >
> > > On 2021.02.15. 12:31 Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > > On Mon, Feb 15, 2021 at 11:53 AM vignesh C <vignesh21(at)gmail(dot)com> wrote:
> > > > On Sat, Feb 13, 2021 at 5:58 PM Erik Rijkers <er(at)xs4all(dot)nl> wrote:
> > > > > I compiled just now a binary from HEAD, and a binary from HEAD+patch
> > > > > HEAD is still broken; your patch rescues it, so yes, fixed.
> > > > > Maybe a test (check or check-world) should be added to run a second replica? (Assuming that would have caught this bug)
> > > > >
> > > > +1 for the idea of having a test for this. I have written a test for this.
> > > > Thanks for the fix Amit, I could reproduce the issue without your fix
> > > > and verified that the issue gets fixed with the patch you shared.
> > > > Attached a patch for the same. Thoughts?
> > > >
> > >
> > > I have slightly modified the comments in the test case to make things
> > > clear. I am planning not to backpatch this because there is no way in
> > > the core code to hit this prior to commit ce0fdbfe97 and we haven't
> > > received any complaints so far. What do you think?
> >
> > My tests indeed run OK with this.
> >
> > (I haven't tested whether the newly added test actually tests for the problem that was there - I suppose one of you did that)
> >
>
> I could re-create the scenario that you had faced with this test. This
> test case is a simplified test of your script, I have removed the use
> of pgbench, reduced the number of tables used and simulated the same
> problem with the similar replication setup that you had used.
>

Yeah, I was also able to see an issue with this test without a patch
and it got fixed after the patch. Pushed!

--
With Regards,
Amit Kapila.

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