Re: Fix 035_standby_logical_decoding.pl race conditions

Hi Kuroda-san,

On Tue, Apr 01, 2025 at 01:22:49AM +0000, Hayato Kuroda (Fujitsu) wrote:
> Dear Bertrand,
>

Thanks for the updated patch!

> > s/to avoid the seeing a xl_running_xacts/to avoid seeing a xl_running_xacts/?
>
> Fixed.

hmm, not sure as I still can see:

+# Note that injection_point is used to avoid the seeing the xl_running_xacts

=== 1

+ * XXX What value should we return here? Originally this returns the
+ * inserted location of RUNNING_XACT record. Based on that, here
+ * returns the latest insert location for now.
+ */
+ return GetInsertRecPtr();

Looking at the LogStandbySnapshot() that are using the output lsn, i.e:

pg_log_standby_snapshot()
BackgroundWriterMain()
ReplicationSlotReserveWal()

It looks ok to me to use GetInsertRecPtr().

But if we "really" want to produce a "new" WAL record, what about using
LogLogicalMessage()? It could also be used for debugging purpose. Bonus point:
it does not need wal_level to be set to logical. Thoughts?

Regards,

--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com