Re: [BUG?] check_exclusion_or_unique_constraint false negative

On Fri, Aug 2, 2024 at 10:38 PM Michail Nikolaev
<michail(dot)nikolaev(at)gmail(dot)com> wrote:
>
> > I think it is rather less likely or not possible in a parallel apply
> > case because such conflicting updates (updates on the same tuple)
> > should be serialized at the publisher itself. So one of the updates
> > will be after the commit that has the second update.
>
> Glad to hear! But anyway, such logic looks very fragile to me.
>
> > I haven't tried the test based on your description of the general
> > problem with DirtySnapshot scan. In case of logical replication, we
> > will LOG update_missing type of conflict and the user may need to take
> > some manual action based on that.
>
> Current it is just DEBUG1, so it will be probably missed by the user.
>
> > * XXX should this be promoted to ereport(LOG) perhaps?
> > */
> > elog(DEBUG1,
> > "logical replication did not find row to be updated "
> > "in replication target relation \"%s\"",
> > RelationGetRelationName(localrel));
> > }
>

Right, but we are extending this functionality to detect and resolve
such conflicts [1][2]. I am hoping after that such updates won't be
missed.

[1] - https://commitfest.postgresql.org/49/5064/
[2] - https://commitfest.postgresql.org/49/5021/

--
With Regards,
Amit Kapila.