RE: Conflict detection and logging in logical replication

Zhijie Hou (Fujitsu) <houzj.fnst@fujitsu.com>

From: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
To: shveta malik <shveta.malik@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Nisha Moond <nisha.moond412@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Dilip Kumar <dilipbalaut@gmail.com>, Jan Wieck <jan@wi3ck.info>, Peter Smith <smithpb2250@gmail.com>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: 2024-08-28T04:11:07Z
Lists: pgsql-hackers

Attachments

On Wednesday, August 28, 2024 11:30 AM shveta malik <shveta.malik@gmail.com> wrote:
> 
> On Tue, Aug 27, 2024 at 4:37 AM Peter Smith <smithpb2250@gmail.com>
> wrote:
> >
> > On Mon, Aug 26, 2024 at 7:52 PM Amit Kapila <amit.kapila16@gmail.com>
> wrote:
> > >
> > > On Thu, Aug 22, 2024 at 2:21 PM Amit Kapila <amit.kapila16@gmail.com>
> wrote:
> > > >
> > > > On Thu, Aug 22, 2024 at 1:33 PM Peter Smith
> <smithpb2250@gmail.com> wrote:
> > > > >
> > > > > Do you think the documentation for the 'column_value' parameter
> > > > > of the conflict logging should say that the displayed value
> > > > > might be truncated?
> > > > >
> > > >
> > > > I updated the patch to mention this and pushed it.
> > > >
> > >
> > > Peter Smith mentioned to me off-list that the names of conflict
> > > types 'update_differ' and 'delete_differ' are not intuitive as
> > > compared to all other conflict types like insert_exists,
> > > update_missing, etc. The other alternative that comes to mind for
> > > those conflicts is to name them as
> 'update_origin_differ'/''delete_origin_differ'.
> > >
> >
> > For things to "differ" there must be more than one them. The plural of
> > origin is origins.
> >
> > e.g. 'update_origins_differ'/''delete_origins_differ'.
> >
> > OTOH, you could say "differs" instead of differ:
> >
> > e.g. 'update_origin_differs'/''delete_origin_differs'.
> >
> 
> +1 on 'update_origin_differs' instead of 'update_origins_differ' as
> the former is somewhat similar to other conflict names 'insert_exists'
> and 'update_exists'.

Since we reached a consensus on this, I am attaching a small patch
to rename as suggested.

Best Regards,
Hou zj

Commits

  1. Rename the conflict types for the origin differ cases.

  2. Doc: explain the log format of logical replication conflicts.

  3. Log the conflicts while applying changes in logical replication.

  4. Avoid duplicate table scans for cross-partition updates during logical replication.