Horton

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

vignesh C <vignesh21@gmail.com>

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From: vignesh C <vignesh21@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Alexander Lakhin <exclusion@gmail.com>, Noah Misch <noah@leadboat.com>, pgsql-hackers@lists.postgresql.org
Date: 2024-02-07T10:57:10Z
Lists: pgsql-hackers

Attachments

On Wed, 7 Feb 2024 at 15:21, Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Tue, Feb 6, 2024 at 8:21 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> >
> > Amit Kapila <amit.kapila16@gmail.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

Commits

  1. Back-patch test modifications that were done as part of b6df0798a5.

  2. Fix the intermittent buildfarm failures in 031_column_list.

  3. Fix test race between primary XLOG_RUNNING_XACTS and standby logical slot.

  4. Bound waits in 035_standby_logical_decoding.pl.