Re: Conflict detection and logging in logical replication

shveta malik <shveta.malik@gmail.com>

From: shveta malik <shveta.malik@gmail.com>
To: Peter Smith <smithpb2250@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.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>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, shveta malik <shveta.malik@gmail.com>
Date: 2024-08-28T03:30:17Z
Lists: pgsql-hackers
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'.

thanks
Shveta



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.