Re: Proposal: Conflict log history table for Logical Replication

On Tue, Sep 23, 2025 at 11:29 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> On Sat, Sep 20, 2025 at 4:59 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> >
> > AFAIR, one open point for internally created tables is whether we
> > should skip changes to conflict_history table while replicating
> > changes? The table will be considered under for ALL TABLES
> > publications, if defined? Ideally, these should behave as catalog
> > tables, so one option is to mark them as 'user_catalog_table', or the
> > other option is we have some hard-code checks during replication. The
> > first option has the advantage that it won't write additional WAL for
> > these tables which is otherwise required under wal_level=logical. What
> > other options do we have?
>
> I think conflict history information is subscriber local information
> so doesn't have to be replicated to another subscriber. Also it could
> be problematic in cross-major-version replication cases if we break
> the compatibility of history table definition.
>

Right, this is another reason not to replicate it.

> I would expect that the
> history table works as a catalog table in terms of logical
> decoding/replication. It would probably make sense to reuse the
> user_catalog_table option for that purpose. If we have a history table
> for each subscription that wants to record the conflict history (I
> believe so), it would be hard to go with the second option (having
> hard-code checks).
>

Agreed. Let's wait and see what Dilip or others have to say on this.

--
With Regards,
Amit Kapila.