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

Noah Misch <noah(at)leadboat(dot)com> writes:
> On Fri, Feb 02, 2024 at 05:07:14PM -0500, Tom Lane wrote:
>> If you look at the buildfarm's failures page and filter down to
>> just subscriptionCheck failures, what you find is that all of the
>> last 6 such failures are in 031_column_list.pl:
>> ...
>> I don't see anything that 031_column_list.pl is doing that is much
>> different from other subscription tests, so why is it the only one
>> failing? And more to the point, what's going wrong exactly?

> I don't know, but
> https://www.postgresql.org/message-id/flat/16d6d9cc-f97d-0b34-be65-425183ed3721%40gmail.com
> reported a replacement BgWriterDelay value reproducing it. That hasn't
> reproduced it in ~10 runs on my machine, though.

Ah, thanks for that link. I like the theory proposed in that thread
that the walsender is starting up at an LSN somewhere before where
the publication is created. I'm tempted to add some more queries to
the test script to see if that can be proven.

I'm still wondering how come the failure seems to have suddenly gotten
way more common. The only changes that are in vaguely-related places
and fit the time frame are Amit's 732924043 and 776621a5e, but I sure
don't see a connection.

regards, tom lane