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: Greg Nancarrow <gregn4422@gmail.com>, vignesh C <vignesh21@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, "osumi.takamichi@fujitsu.com" <osumi.takamichi@fujitsu.com>, Alexey Lesovsky <lesovsky@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2021-12-16T05:21:32Z
Lists: pgsql-hackers 
On Thu, Dec 16, 2021 at 10:37 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> On Thu, Dec 16, 2021 at 11:43 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > I thought we just want to lock before clearing the skip_xid something
> > like take the lock, check if the skip_xid in the catalog is the same
> > as we have skipped, if it is the same then clear it, otherwise, leave
> > it as it is. How will that disallow users to change skip_xid when we
> > are skipping changes?
>
> Oh I thought we wanted to keep holding the lock while skipping changes
> (changing skip_xid requires acquiring the lock).
>
> So if skip_xid is already changed, the apply worker would do
> replorigin_advance() with WAL logging, instead of committing the
> catalog change?
>

Right. BTW, how are you planning to advance the origin? Normally, a
commit transaction would do it but when we are skipping all changes,
the commit might not do it as there won't be any transaction id
assigned.

-- 
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