Re: pg_upgrade link mode

On Thu, May 16, 2013 at 02:21:16PM -0400, AI Rumman wrote:
> I told you I would never go for a production with link mode. However, I was
> working with pg_upgrade copy mode and in the middle I got an error saying
> missing some extensions. I rollback and start the operation after setting
> everything up.
> I don't know how it will behave in link mode if you fail in the middle.

I guess a lot of people prefer to guess about the risks of --link mode
rather than read the pg_upgrade manual, which says:

http://www.postgresql.org/docs/9.3/static/pgupgrade.html

If you use link mode, the upgrade will be much faster (no file copying),
but you will not be able to access your old cluster once you start the
new cluster after the upgrade. Link mode also requires that the old and
new cluster data directories be in the same file system. See pg_upgrade
--help for a full list of options.

So, no, you don't get a mess if the upgrade fails in the middle, even in
link mode, but you would be in trouble if you started the new server and
wanted to revert to the old server.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +