Re: Logical replication 'invalid memory alloc request size 1585837200' after upgrading to 17.5

On Fri, 20 Jun 2025 at 13:51, Hayato Kuroda (Fujitsu)
<kuroda(dot)hayato(at)fujitsu(dot)com> wrote:
>
> Dear hackers,
>
> I've analyzed the issue, and this can always happen when --DCLOBBER_CACHE_ALWAYS is
> set on PG13. My suggestion is to remove the latter part of test on this branch.
>
> In the failed workload, we tested the case that one long transaction inserts a
> tuple after the concurrent transaction does ALTER PUBLICATION ADD TABLE.
> For PG14+ the change can be published, and PG13 it cannot be replicated because
> the distributed inval messages cannot be executed during the transaction. That's
> why we expected no results were output.
>
> So what if the -DDCLOBBER_CACHE_ALWAYS is set for the workload? relsync cache
> can be discarded very frequently and backend process always read the system
> catalog when it processes their changes. This means decoder can recognize that the
> pg_publication has been updated and it can publish changes based on the altered
> publication information. This behavior is opposite from normal.

I agree with your analysis.

> To fix the test failure, I suggest to just remove the case. Insert-after-commit
> case has already been tested by above part of this file, so no need to do others.

Alternatively I was thinking of a fix if it is possible to run this
test conditionally when CLOBBER_CACHE_ALWAYS is not defined, I was not
sure if it is easy to do that and worth the effort for the PG13
branch. I'm ok with the proposed change.

Regards,
Vignesh