Re: Logical replication timeout problem

On Fri, Mar 25, 2022 at 11:49 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> On Fri, Mar 25, 2022 at 2:23 PM wangw(dot)fnst(at)fujitsu(dot)com
> <wangw(dot)fnst(at)fujitsu(dot)com> wrote:
>
> Since commit 75b1521 added decoding of sequence to logical
> replication, the patch needs to have pgoutput_sequence() call
> update_progress().
>

Yeah, I also think this needs to be addressed. But apart from this, I
want to know your and other's opinion on the following two points:
a. Both this and the patch discussed in the nearby thread [1] add an
additional parameter to
WalSndUpdateProgress/OutputPluginUpdateProgress and it seems to me
that both are required. The additional parameter 'last_write' added by
this patch indicates: "If the last write is skipped then try (if we
are close to wal_sender_timeout) to send a keepalive message to the
receiver to avoid timeouts.". This means it can be used after any
'write' message. OTOH, the parameter 'skipped_xact' added by another
patch [1] indicates if we have skipped sending anything for a
transaction then sendkeepalive for synchronous replication to avoid
any delays in such a transaction. Does this sound reasonable or can
you think of a better way to deal with it?
b. Do we want to backpatch the patch in this thread? I am reluctant to
backpatch because it changes the exposed API which can have an impact
and second there exists a workaround (user can increase
wal_sender_timeout/wal_receiver_timeout).

[1] - https://www.postgresql.org/message-id/OS0PR01MB5716BB24409D4B69206615B1941A9%40OS0PR01MB5716.jpnprd01.prod.outlook.com

--
With Regards,
Amit Kapila.