Re: [HACKERS] logical decoding of two-phase transactions

On Wed, Nov 25, 2020 at 11:54 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:

> One problem with this patch is: What if we have assembled a consistent
> snapshot after prepare and before commit prepared. In that case, it
> will currently just send commit prepared record which would be a bad
> idea. It should decode the entire transaction for such cases at commit
> prepared time. This same problem is noticed by Arseny Sher, see
> problem-2 in email [1].

I'm not sure I understand how you could assemble a consistent snapshot
after prepare but before commit prepared?
Doesn't a consistent snapshot require that all in-progress
transactions commit? I've tried start a new subscription after
a prepare on the publisher and I see that the create subscription just
hangs till the transaction on the publisher is either committed or
rolled back.
Even if I try to create a replication slot using
pg_create_logical_replication_slot when a transaction has been
prepared but not yet committed
, it just hangs till the transaction is committed/aborted.

regards,
Ajin Cherian
Fujitsu Australia