Re: Lost replication slots after pg_upgrade.

Hi,

I think Nikhil was going to invoke the rsync black magic as described
> in https://www.postgresql.org/docs/current/pgupgrade.html, not for
> copying the entire PGDATA from the master to standbys. While the rsync
> magic should be hundreds of times faster because only modified files
> will be copied and the majority of files will be just hardlinked, I've
> never felt I have enough skill and luck to undertake this method.

Yes, I am using rsync only to copy modified files.

Because pg_upgrade basically runs initdb for you. You are dealing with
> a new cluster after pg_upgrade, in fact.

Thanks for the details Victor and Julien.

Thanks,
Nikhil

On Tue, Feb 8, 2022 at 2:15 PM Julien Rouhaud <rjuju123(at)gmail(dot)com> wrote:

> On Tue, Feb 08, 2022 at 08:32:22AM +0000, Victor Sudakov wrote:
> > Julien Rouhaud wrote:
> > >
> > > > pg_basebackup takes time for large databases (> 5TB). I feel rsync
> should
> > > > be faster.
> > >
> > > Not necessarily. pg_basebackup will do simple sequential read of all
> the data,
> > > which is probably the fastest thing to do. rsync will do some extra
> processing
> > > that isn't required in that scenario, so it's likely to be slower
> (although
> > > probably only marginally slower).
> >
> > I think Nikhil was going to invoke the rsync black magic as described
> > in https://www.postgresql.org/docs/current/pgupgrade.html, not for
> > copying the entire PGDATA from the master to standbys. While the rsync
> > magic should be hundreds of times faster because only modified files
> > will be copied and the majority of files will be just hardlinked, I've
> > never felt I have enough skill and luck to undertake this method.
>
> Ah, if that's the case I don't think there's any doubt to have for rsync
> being
> faster. And this method works just fine if you take care of what you're
> doing.
>