Re: logical decoding and replication of sequences, take 2

On Wed, Dec 6, 2023 at 11:12 AM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
>
> On Sun, Dec 3, 2023 at 11:22 PM Tomas Vondra
> <tomas(dot)vondra(at)enterprisedb(dot)com> wrote:
> >
>
> > Some time ago I floated the idea of maybe "queuing" the sequence changes
> > and only replay them on the next commit, somehow. But we did ran into
> > problems with which snapshot to use, that I didn't know how to solve.
> > Maybe we should try again. The idea is we'd queue the non-transactional
> > changes somewhere (can't be in the transaction, because we must keep
> > them even if it aborts), and then "inject" them into the next commit.
> > That'd mean we wouldn't do the separate start/abort for each change.
>
> Why can't we use the same concept of
> SnapBuildDistributeNewCatalogSnapshot(), I mean we keep queuing the
> non-transactional changes (have some base snapshot before the first
> change), and whenever there is any catalog change, queue new snapshot
> change also in the queue of the non-transactional sequence change so
> that while sending it to downstream whenever it is necessary we will
> change the historic snapshot?
>

Oh, do you mean maintain different historic snapshots and then switch
based on the change we are processing? I guess the other thing we need
to consider is the order of processing the changes if we maintain
separate queues that need to be processed.

--
With Regards,
Amit Kapila.