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: Greg Nancarrow <gregn4422@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: 2021-10-28T05:25:33Z
Lists: pgsql-hackers 
On Thu, Oct 28, 2021 at 1:29 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Wed, Oct 27, 2021 at 4:07 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Wed, Oct 27, 2021 at 8:32 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> > >
> > > On Tue, Oct 26, 2021 at 7:29 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > > >
> > > > You have a point. The other alternatives on this line could be:
> > > >
> > > > Alter Subscription <sub_name> SKIP ( subscription_parameter [=value] [, ... ] );
> > > >
> > > > where subscription_parameter can be one of:
> > > > xid = <xid_val>
> > > > lsn = <lsn_val>
> > > > ...
> > >
> > > Looks better.
> > >
> >
> > If we want to follow the above, then how do we allow users to reset
> > the parameter? One way is to allow the user to set xid as 0 which
> > would mean that we reset it. The other way is to allow SET/RESET
> > before SKIP but not sure if that is a good option.
> >
>
> After thinking some more on this, I think it is better to not use
> SET/RESET keyword here. I think we can use a model similar to how we
> allow setting some of the options in Alter Database:
>
> # Set the connection limit for a database:
> Alter Database akapila WITH connection_limit = 1;
> # Reset the connection limit
> Alter Database akapila WITH connection_limit = -1;
>
> Thoughts?

Agreed.

Another thing I'm concerned is that the syntax "SKIP (
subscription_parameter [=value] [, ...])" looks like we can specify
multiple options for example, "SKIP (xid = '100', lsn =
'0/12345678’)”. Is there a case where we need to specify multiple
options? Perhaps when specifying the target XID and operations for
example, “SKIP (xid = 100, action = ‘insert, update’)”?

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