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: 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>, Greg Nancarrow <gregn4422@gmail.com>
Date: 2021-10-04T05:31:24Z
Lists: pgsql-hackers 
On Mon, Oct 4, 2021 at 6:01 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> On Fri, Oct 1, 2021 at 5:32 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Fri, Oct 1, 2021 at 6:30 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> > >
> > > On Fri, Oct 1, 2021 at 5:05 AM Peter Eisentraut
> > > <peter.eisentraut@enterprisedb.com> wrote:
> > > >
> > > > On 30.09.21 07:45, Masahiko Sawada wrote:
> > > > > I've attached updated patches that incorporate all comments I got so
> > > > > far. Please review them.
> > > >
> > > > I'm uneasy about the way the xids-to-be-skipped are presented as
> > > > subscriptions options, similar to settings such as "binary".  I see how
> > > > that is convenient, but it's not really the same thing, in how you use
> > > > it, is it?  Even if we share some details internally, I feel that there
> > > > should be a separate syntax somehow.
> > >
> > > Since I was thinking that ALTER SUBSCRIPTION ... SET is used to alter
> > > parameters originally set by CREATE SUBSCRIPTION, in the first several
> > > version patches it added a separate syntax for this feature like ALTER
> > > SUBSCRIPTION ... SET SKIP TRANSACTION xxx. But Amit was concerned
> > > about an additional syntax and consistency with disable_on_error[1]
> > > which is proposed by Mark Diliger[2], so I’ve changed it to a
> > > subscription option.
> > >
> >
> > Yeah, the basic idea is that this is not the only option we will
> > support for taking actions on error/conflict. For example, we might
> > want to disable subscriptions or allow skipping transactions based on
> > XID, LSN, etc.
>
> I guess disabling subscriptions on error/conflict and skipping the
> particular transactions are somewhat different types of functions.
> Disabling subscriptions on error/conflict seems likes a setting
> parameter of subscriptions. The users might want to specify this
> option at creation time.
>

Okay, but they can still specify it by using "On Error" syntax.

> Whereas, skipping the particular transaction
> is a repair function that the user might want to use on the spot in
> case of a failure. I’m concerned a bit that combining these functions
> to one syntax could confuse the users.
>

Fair enough, I was mainly trying to combine the syntax for all actions
that we can take "On Error". We can allow to set them either at Create
Subscription or Alter Subscription time.

I think here the main point is that does this addresses Peter's
concern for this Patch to use a separate syntax? Peter E., can you
please confirm? Do let us know if you have something else going in
your mind?

-- 
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