Re: Conflict Detection and Resolution

On Tue, Jul 30, 2024 at 4:56 PM shveta malik <shveta(dot)malik(at)gmail(dot)com> wrote:
>
> On Tue, Jul 30, 2024 at 4:04 PM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> >
> > On Fri, Jul 26, 2024 at 9:50 AM Ajin Cherian <itsajin(at)gmail(dot)com> wrote:
> >
> > Comment in 0002,
> >
> > 1) I do not see any test case that set a proper conflict type and
> > conflict resolver, all tests either give incorrect conflict
> > type/conflict resolver or the conflict resolver is ignored
> >
> > 0003
> > 2) I was trying to think about this patch, so suppose we consider this
> > case conflict_type-> update_differ resolver->remote_apply, my
> > question is to confirm whether my understanding is correct. So if
> > this is set and we have 2 nodes and set up a 2-way logical
> > replication, and if a conflict occurs node-1 will take the changes of
> > node-2 and node-2 will take the changes of node-1?
>
> Yes, that's right.
>
> > Maybe so I think
> > to avoid such cases user needs to set the resolver more thoughtfully,
> > on node-1 it may be set as "skip" and on node-1 as "remote-apply" so
> > in such cases if conflict happens both nodes will have the value from
> > node-1. But maybe it would be more difficult to get a consistent
> > value if we are setting up a mess replication topology right? Maybe
> > there I think a more advanced timestamp-based option would work better
> > IMHO.
>
> Yes, that's correct. We can get data divergence with resolvers like
> 'remote_apply', 'keep_local' etc. If you meant 'mesh' replication
> topology, then yes, it is difficult to get consistent value there with
> resolvers other than timestamp based. And thus timestamp based
> resolvers are needed and should be the default when implemented.
>

Thanks for the clarification.

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com