From: Stephen Frost <sfrost@snowman.net>
To: Bruce Momjian <bruce@momjian.us>
Cc: Fabio Pardi <f.pardi@portavita.eu>
Cc: pgsql-performance@lists.postgresql.org
Subject: Re: Fwd: upgrade to PG11 on secondary fails (no initdb was launched)
Date: Fri, 14 Jun 2019 12:15:38 -0400
Message-ID: <20190614161538.GH2480@tamriel.snowman.net> (raw)
In-Reply-To: <20190614144409.bmrlzgnu4ibhz2cr@momjian.us>
References: <CA+t6e1nixp7tqTS3m1tV+XxC45gL8XG6JtSt5QdLYwBTCW3WmA@mail.gmail.com>
<CA+t6e1k-xEkjhUTnLik8MCf7-Sb+ek71jsZVN0ewduLEBy0iPw@mail.gmail.com>
<68cf5e6c-8eb0-d8dc-08ec-78d8e910c17c@portavita.eu>
<20190614033001.5jif725fxchtopg7@momjian.us>
<b07e8a66-b122-8f41-03b3-6d2fc236f3e7@portavita.eu>
<20190614143940.vux2quolie4s6luv@momjian.us>
<20190614144409.bmrlzgnu4ibhz2cr@momjian.us>
Greetings,
* Bruce Momjian (bruce@momjian.us) wrote:
> On Fri, Jun 14, 2019 at 10:39:40AM -0400, Bruce Momjian wrote:
> > On Fri, Jun 14, 2019 at 03:12:29PM +0200, Fabio Pardi wrote:
> > > Using --size-only, tells rsync to only check the size of the blocks.
> > > That is: if the block is present on the destination, and is the same
> > > size as the origin, then skip.
> >
> > The files are _exactly_ the same on primary and standby, so we don't
> > need to check anything. Frankly, it is really only doing hard linking
> > of the files.
>
> Here is the description from our docs:
>
> What this does is to record the links created by pg_upgrade's
> link mode that connect files in the old and new clusters on the
> primary server. It then finds matching files in the standby's old
> cluster and creates links for them in the standby's new cluster.
> Files that were not linked on the primary are copied from the
> primary to the standby. (They are usually small.) This provides
> rapid standby upgrades. Unfortunately, rsync needlessly copies
> files associated with temporary and unlogged tables because these
> files don't normally exist on standby servers.
>
> The primary and standby have to be binary the same or WAL replay would
> not work on the standby. (Yes, I sometimes forgot how this worked so I
> wrote it down in the docs.) :-)
Right- this is *not* a general process for building a replica, this is
specifically *only* for when doing a pg_upgrade and *everything* is shut
down when it runs, and every step is checked to ensure that there are no
errors during the process.
Thanks!
Stephen
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To: pgsql-performance@postgresql.org
Cc: sfrost@snowman.net, bruce@momjian.us, f.pardi@portavita.eu, pgsql-performance@lists.postgresql.org
Subject: Re: Fwd: upgrade to PG11 on secondary fails (no initdb was launched)
In-Reply-To: <20190614161538.GH2480@tamriel.snowman.net>
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