On Mon, Oct 12, 2026 at 10:26 AM Amit Kapila <[email protected]> wrote:
>
> On Fri, Sep 18, 2026 at 1:58 PM shveta malik <[email protected]> wrote:
> >
> > On Fri, Sep 18, 2026 at 1:35 PM Nisha Moond <[email protected]> 
> > wrote:
> > >
> > > On Thu, Sep 17, 2026 at 8:06 PM Dilip Kumar <[email protected]> wrote:
> > >
> > > 2) Now that remote_tuple has been removed, there is some information
> > > loss when the replica identity key itself is updated.
> > > For example:
> > > -- pub
> > > INSERT INTO t1 VALUES (3,'three');
> > > -- sub
> > > DELETE FROM t1 WHERE a = 3;
> > > -- pub
> > > UPDATE t1 SET a = 30 WHERE a = 3;
> > >
> > > Server log:
> > >   conflict detected on relation "public.t1": conflict=update_missing
> > >   DETAIL:  Could not find the row to be updated: remote row (30,
> > > three), replica identity (a)=(3).
> > >
> > > Conflict log table: replica_identity = {"a":3}, and there is no
> > > mention of the new key 30 anywhere.
> > >
> > > For update_missing the remote change is skipped, but for
> > > update_origin_differs the change is applied, so the local row now has
> > > a=30 while the CLT row names a=3, and nothing connects the two. The
> > > log will show the remote tuple, though.
> >
> > I agree. I too noticed this. Need to think more here.
> >
> > Another point of concern: we don't know from the CLT which column
> > conflicted, out of the potentially large number of columns in a user
> > tab. Consider an update_origin_differs case:
> >
> > Table t(id PK, val), with id=10, val=20 on both nodes.
> >
> > On the subscriber, the row is changed to val=200.
> > At the same time, on the publisher, it is changed to val=300.
> >
> > The publisher's change comes in as an update_origin_differs conflict
> > and overwrites 200 with 300. But the CLT only records something like:
> >
> > SELECT conflict_type, replica_identity, local_conflicts FROM
> > pg_conflict.pg_conflict_log_16390;
> > update_origin_differs | {"id":10} | [{"xid":"...", "commit_ts":"...",
> > "origin":null}]
> >
> > So we know row id=10 had a conflict, but not which column conflicted,
> > or what the old and new values were. Is there a concrete way for a
> > user to find that information given only the CLT? Is changed col info
> > worth adding to CLT?
> >
>
> I see that both what you and Nisha reported have value in terms of
> giving more information to users. But OTOH we can add this additional
> information as a separate enhancement as well, as this information
> will also have all kinds of complications w.r.t size of data shouldn't
> be more than 1GB.
>

Okay. Works for me. We can explore these as further enhancements.
Basically these:

1) When the replica identity (RI) itself changes, we can explore
logging both the new and old RI values.
2) We can look into logging the 'conflicted column': name and value.

thanks
Shveta


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