Horton

Re: Skipping logical replication transactions on subscriber side

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2021-05-26T09:11:46Z
Lists: pgsql-hackers 
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.

-- 
With Regards,
Amit Kapila.

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