RE: Doc: fix the note related to the GUC "synchronized_standby_slots"

masahiro.ikeda@nttdata.com

From: <Masahiro.Ikeda@nttdata.com>
To: <amit.kapila16@gmail.com>
Cc: <pgsql-hackers@lists.postgresql.org>, <Masao.Fujii@nttdata.com>
Date: 2024-08-28T00:46:12Z
Lists: pgsql-hackers
> > > So, will it be okay if we just remove ".. without losing data" from
> > > the sentence? Will that avoid the confusion you have?
> > Yes. Additionally, it would be better to add notes about data
> > consistency after failover for example
> >
> > Note that data consistency after failover can vary depending on the
> > configurations. If "synchronized_standby_slots" is not configured,
> > there may be data that only the subscribers hold, even though the new primary does
> not.
> >
> 
> This part can be inferred from the description of synchronized_standby_slots [1] (See:
> This guarantees that logical replication failover slots do not consume changes until those
> changes are received and flushed to corresponding physical standbys. If a logical
> replication connection is meant to switch to a physical standby after the standby is
> promoted, the physical replication slot for the standby should be listed here.)

OK, it's enough for me just remove ".. without losing data".

> >
>  Additionally, in the case of asynchronous physical replication,
> > there remains a risk of data loss for transactions committed on the
> > former primary server but have yet to be replicated to the new primary server.
> >
> 
> This has nothing to do with failover slots. This is a known behavior of asynchronous
> replication, so adding here doesn't make much sense.
> 
> In general, adding more information unrelated to failover slots can confuse users.

OK, I agreed to remove the sentence.

Regards,
--
Masahiro Ikeda
NTT DATA CORPORATION



Commits

  1. Doc: Fix the ambiguity in the description of failover slots.