Horton

Re: Skipping logical replication transactions on subscriber side

Masahiko Sawada <sawada.mshk@gmail.com>

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From: Masahiko Sawada <sawada.mshk@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2021-05-27T06:30:48Z
Lists: pgsql-hackers 
On Wed, May 26, 2021 at 6:11 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Tue, May 25, 2021 at 6:12 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> >
> > On Tue, May 25, 2021 at 7:21 PM Bharath Rupireddy
> > <bharath.rupireddyforpostgres@gmail.com> wrote:
> > >
> > > If there's no way to get the "correct LSN", then why can't we just
> > > print that LSN in the error context and/or in the new statistics view
> > > for logical replication workers, so that any of the existing ways can
> > > be used to skip exactly one txn?
> >
> > I think specifying XID to the subscription is more understandable for users.
> >
>
> I agree with you that specifying XID could be easier and
> understandable for users. I was thinking and studying a bit about what
> other systems do in this regard. Why don't we try to provide conflict
> resolution methods for users? The idea could be that either the
> conflicts can be resolved automatically or manually. In the case of
> manual resolution, users can use the existing methods or the XID stuff
> you are proposing here and in case of automatic resolution, the
> in-built or corresponding user-defined functions will be invoked for
> conflict resolution. There are more details to figure out in the
> automatic resolution scheme but I see a lot of value in doing the
> same.

Yeah, I also see a lot of value in automatic conflict resolution. But
maybe we can have both ways? For example, in case where the user wants
to resolve conflicts in different ways or a conflict that cannot be
resolved by automatic resolution (not sure there is in practice
though), the manual resolution would also have value.

Regards,

--
Masahiko Sawada
EDB:  https://www.enterprisedb.com/

Commits

  1. Test ALIGNOF_DOUBLE==4 compatibility under ALIGNOF_DOUBLE==8.

  2. Reorder subskiplsn in pg_subscription to avoid alignment issues.

  3. Add ALTER SUBSCRIPTION ... SKIP.

  4. Optionally disable subscriptions on error.

  5. Update docs of logical replication for commit 8d74fc96db.

  6. Respect permissions within logical replication.

  7. Fix regression test failure caused by commit 8d74fc96db.

  8. Add a view to show the stats of subscription workers.

  9. Add logical change details to logical replication worker errcontext.

  10. Rename LOGICAL_REP_MSG_STREAM_END to LOGICAL_REP_MSG_STREAM_STOP.

  11. Fix typo in protocol.sgml.

  12. Remove unused argument in apply_handle_commit_internal().

  13. Fix replication of in-progress transactions in tablesync worker.

  14. Reorder pg_sequence columns to avoid alignment issue