Re: Multi-Master Logical Replication

On Sat, May 14, 2022 at 12:20:05PM +0530, Amit Kapila wrote:
> On Sat, May 14, 2022 at 12:33 AM Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> >
> > Uh, without these features, what workload would this help with?
> >
>
> To allow replication among multiple nodes when some of the nodes may
> have pre-existing data. This work plans to provide simple APIs to
> achieve that. Now, let me try to explain the difficulties users can
> face with the existing interface. It is simple to set up replication
> among various nodes when they don't have any pre-existing data but
> even in that case if the user operates on the same table at multiple
> nodes, the replication will lead to an infinite loop and won't
> proceed. The example in email [1] demonstrates that and the patch in
> that thread attempts to solve it. I have mentioned that problem
> because this work will need that patch.
...
> This will become more complicated when more than two nodes are
> involved, see the example provided for the three nodes case [2]. Can
> you think of some other simpler way to achieve the same? If not, I
> don't think the current way is ideal and even users won't prefer that.
> I am not telling that the APIs proposed in this thread is the only or
> best way to achieve the desired purpose but I think we should do
> something to allow users to easily set up replication among multiple
> nodes.

You still have not answered my question above. "Without these features,
what workload would this help with?" You have only explained how the
patch would fix one of the many larger problems.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

Indecision is a decision. Inaction is an action. Mark Batterson