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

On Fri, May 30, 2025 at 9:31 AM vignesh C <vignesh21(at)gmail(dot)com> wrote:
>
> On Thu, 29 May 2025 at 22:57, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> >
> > > I agree that chances are much lower than current if txn->invalidations
> > > doesn't contain invalidations from other transactions, but it is not
> > > clear what exactly you are trying to advocate by it. Are you trying to
> > > advocate that we should maintain a member similar to txn->invalidation
> > > (say txn->distributed_invals) instead of a queue?
> >
> > Yes, because I guess it's much simpler. I think it would not be a good
> > idea to introduce a new concept of accounting the memory usage of the
> > distributed inval messages too and serializing them, at least on back
> > branches. I think that In case where the txn->distriubted_inval is
> > about to overflow (not has to be 1GB) we can invalidate all caches
> > instread.
>

I agree that it would be simpler, and to avoid invalid memory
allocation requests even for rare cases, we can have the backup logic
to invalidate all caches.

> To identify overflow scenarios, I’m considering the following options:
> a) Introduce a new txn_flags value, such as RBTXN_INVAL_ALL_CACHE, to
> explicitly mark transactions that require full cache invalidation.
> b) Add a dedicated parameter to indicate an overflow scenario.
> c) setting the newly added nentries_distr to -1, to indicate an
> overflow scenario.
>
> Do you have any preference or thoughts on which of these approaches
> would be cleaner?
>

I would prefer (a) as that is an explicit way to indicate that we need
to invalidate all caches. But let us see if Sawada-san has something
else in mind.

--
With Regards,
Amit Kapila.