Re: Conflict detection for update_deleted in logical replication

On Tue, May 27, 2025 at 11:45 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Mon, May 26, 2025 at 12:46 PM Zhijie Hou (Fujitsu)
> <houzj(dot)fnst(at)fujitsu(dot)com> wrote:
> >
> > On Sun, May 25, 2025 at 4:36 PM Dilip Kumar wrote:
> >
> > >
> > > I am thinking can't we make it more deterministic such that when we
> > > get the status first time if we find some transactions that are in
> > > commit phase then we should just wait for those transaction to get
> > > committed? One idea is to get the list of xids in commit phase and
> > > next time when we get the list we can just compare and in next status
> > > if we don't get any xids in commit phase which were in commit phase
> > > during previous status then we are done. But not sure is this worth
> > > the complexity? Mabe not but shall we add some comment explaining the
> > > case and also explaining why this corner case is not harmful?
> >
> > I also think it's not worth the complexity for this corner case which is
> > rare.
>
> Yeah, complexity is one part, but I feel improving such less often
> cases could add performance burden for more often cases where we need
> to either maintain and invalidate the cache on the publisher or send
> the list of all such xids to the subscriber over the network.

Yeah, that's a valid point.

> > So, I have added some comments in wait_for_publisher_status() to
> > mention the same.
> >
>
> I agree that at this stage it is good to note down in comments, and if
> we face such cases often, then we can improve it in the future.

+1

--
Regards,
Dilip Kumar
Google