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: Greg Nancarrow <gregn4422@gmail.com>
Cc: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Amit Kapila <amit.kapila16@gmail.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, "osumi.takamichi@fujitsu.com" <osumi.takamichi@fujitsu.com>, Alexey Lesovsky <lesovsky@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2021-09-24T13:16:09Z
Lists: pgsql-hackers 
On Fri, Sep 24, 2021 at 5:27 PM Greg Nancarrow <gregn4422@gmail.com> wrote:
>
> On Tue, Sep 21, 2021 at 2:53 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> >
> > I've attached the updated version patches. Please review them.
> >
>
> A few review comments for the v14-0002 patch:

Thank you for the comments!

>
> (1)
> I suggest a small update to the patch comment:
>
> BEFORE:
> ALTER SUBSCRIPTION ... RESET command resets subscription
> parameters. The parameters that can be set are streaming, binary,
> synchronous_commit.
>
> AFTER:
> ALTER SUBSCRIPTION ... RESET command resets subscription
> parameters to their default value. The parameters that can be reset
> are streaming, binary, and synchronous_commit.
>
> (2)
> In the documentation, the RESETable parameters should be listed in the
> same way and order as for SET:
>
> BEFORE:
> +     <para>
> +       The parameters that can be reset are: <literal>streaming</literal>,
> +       <literal>binary</literal>, <literal>synchronous_commit</literal>.
> +     </para>
> AFTER:
> +     <para>
> +       The parameters that can be reset are
> <literal>synchronous_commit</literal>,
> +       <literal>binary</literal>, and <literal>streaming</literal>.
> +      </para>
>
> Also, I'm thinking it would be beneficial to say the following before this:
>
>     RESET is used to set parameters back to their default value.
>

I agreed with all of the above comments. I'll incorporate them into
the next version patch that I'm going to submit next Monday.

> (3)
> I notice that if you try to reset the slot_name, you get the following message:
>     postgres=# alter subscription sub reset (slot_name);
>     ERROR:  unrecognized subscription parameter: "slot_name"
>
> This is a bit misleading, because "slot_name" actually IS a
> subscription parameter, just not resettable.
> It would be better in this case if it said something like:
>     ERROR: not a resettable subscription parameter: "slot_name"
>
> However, it seems that this is also an existing issue with SET (e.g.
> for "refresh" or "two_phase"):
>     postgres=# alter subscription sub set (refresh=true);
>     ERROR:  unrecognized subscription parameter: "refresh"

Good point. Maybe we can improve it in a separate patch?

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