Re: pg_upgrade and rsync

On 2015-01-22 14:20:51 -0500, Bruce Momjian wrote:
> It is possible to upgrade on pg_upgrade on streaming standby servers by
> making them master servers, running pg_upgrade on them, then shuting
> down all servers and using rsync to make the standby servers match the
> real master.

Isn't that a pretty crazy procedure? If you need to shut down all
servers anyway, you can just rsync after having run pg_upgrade on the
master, no? Rsync won't really transfer less just because you ran a
similar thing on the standby.

Even if this would allow to avoid some traffic for fsync: There's
absolutely no guarantee that the standby's pg_upgrade results in a all
that similar data directory. Far from everything in postgres is
deterministic - it's easy to hit timing differences that result in
noticeable differences.

Or do you - as the text edited in your patch, but not the quote above -
mean to run pg_upgrade just on the primary and then rsync?

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services