Re: Why is subscription/t/031_column_list.pl failing so much?

On Wed, 7 Feb 2024 at 15:21, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Tue, Feb 6, 2024 at 8:21 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >
> > Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> writes:
> > > Yeah, I was worried about that. The other idea I have previously
> > > thought was to change Alter Subscription to Drop+Create Subscription.
> > > That should also help in bringing stability without losing any
> > > functionality.
> >
> > Hm, why would that fix it?
> >
>
> Because for new subscriptions, we will start reading WAL from the
> latest WAL insert pointer on the publisher which will be after the
> point where publication is created.

I was able to reproduce the issue consistently with the changes shared
by Tom Lane at [1].
I have made changes to change ALTER SUBSCRIPTION to DROP+CREATE
SUBSCRIPTION and verified that the test has passed consistently for
>50 runs that I ran. Also the test execution time increased for this
case is very negligibly:
Without patch: 7.991 seconds
With test change patch: 8.121 seconds

The test changes for the same are attached.

[1] - https://www.postgresql.org/message-id/631312.1707251789%40sss.pgh.pa.us

Regards,
Vignesh