Date: Tue, 8 Feb 2022 08:32:22 +0000
From: Victor Sudakov <vas@sibptus.ru>
To: Julien Rouhaud <rjuju123@gmail.com>
Cc: Nikhil Shetty <nikhil.dba04@gmail.com>,
	Pgsql-admin <pgsql-admin@lists.postgresql.org>,
	pgsql-admin <pgsql-admin@postgresql.org>
Subject: Re: Lost replication slots after pg_upgrade.
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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.

-- 
Victor Sudakov VAS4-RIPE
http://vas.tomsk.ru/
2:5005/49@fidonet