RE: Time delayed LR (WAS Re: logical replication restrictions)

Dear Amit,

> > > Another related point to consider is what is the behavior of
> > > synchronous replication when shutdown has been performed both in the
> > > case of physical and logical replication especially when the
> > > time-delayed replication feature is enabled?
> >
> > In physical replication without any failures, it seems that users can stop primary
> > server even if the applications are delaying on secondary. This is because sent
> WALs
> > are immediately flushed on secondary and walreceiver replies its position.
> >
> 
> What happens when synchronous_commit's value is remote_apply and the
> user has also set synchronous_standby_names to corresponding standby?

Even if synchronous_commit is set to remote_apply, the primary server can be
shut down. The reason why walsender can exit is that it does not care about the
status whether WALs are "applied" or not. It just checks the "flushed" WAL
position, not applied one.

I think we should start another thread about changing the shut-down condition,
so forked[1].

[1]:
https://www.postgresql.org/message-id/TYAPR01MB586668E50FC2447AD7F92491F5E89%40TYAPR01MB5866.jpnprd01.prod.outlook.com

Best Regards,
Hayato Kuroda
FUJITSU LIMITED