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

On Tue, Dec 1, 2020 at 7:55 AM Ajin Cherian <itsajin(at)gmail(dot)com> wrote:
>
> On Tue, Dec 1, 2020 at 12:46 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
>
>
> > Sure, but you can see in your example above it got skipped due to
> > start_decoding_at not due to DecodingContextReady. So, the problem as
> > mentioned by me previously was how we distinguish those cases because
> > it can skip due to start_decoding_at during restart as well when we
> > would have already sent the prepare to the subscriber.
>
> The distinguishing factor is that at restart, the Prepare does satisfy
> DecodingContextReady (because the snapshot is consistent then).
> In both cases, the prepare is prior to start_decoding_at, but when the
> prepare is before a consistent point,
> it does not satisfy DecodingContextReady.
>

I think it won't be true when we reuse some already serialized
snapshot from some other slot. It is possible that we wouldn't have
encountered such a serialized snapshot while creating a slot but later
during replication, we might use it because by that time some other
slot has serialized the one at that point.

--
With Regards,
Amit Kapila.