Re: pg_upgrade + streaming replication ?

On Mon, Mar 19, 2012 at 03:07:02PM -0700, Jeff Davis wrote:
> On Mon, 2012-03-19 at 15:30 -0400, Bruce Momjian wrote:
> > On Thu, Mar 01, 2012 at 02:01:31PM -0800, Lonni J Friedman wrote:
> > > I've got a 3 node cluster (1 master/2 slaves) running 9.0.x with
> > > streaming replication. I'm in the planning stages of upgrading to
> > > 9.1.x, and am looking into the most efficient way to do the upgrade
> > > with the goal of minimizing downtime & risk. After googling, the only
> > > discussion that I've found of using pg_upgrade with a streaming
> > > replication setup seems to be this (nearly) year old thread:
> > > http://web.archiveorange.com/archive/v/9FNVlDWGQtpyWVL54jlK
> > >
> > > In summary, there is no way to use both pg_upgrade and streaming
> > > replication simultaneously. I'd have to either use pg_upgrade and
> > > then effectively rebuild/redeploy the slaves, or not use pg_upgrade,
> > > and reimport all of the data. Is that still the latest status, or are
> > > there other options?
> >
> > You can shut down all three servers, run pg_upgrade on all of them, then
> > restart them as 9.1 servers.
>
> After running pg_upgrade on each server individually, they will have
> different system IDs, and potentially different on-disk representation
> of the catalogs, right?
>
> So how can you resume streaming without rebuilding the slaves?

Oh, wow, I never thought of the fact that the system tables will be
different? I guess you could assume the pg_dump restore is going to
create things exactly the same on all the systems, but I never tested
that. Do the system id's have to match? That would be a problem
because you are initdb'ing on each server. OK, crazy idea, but I
wonder if you could initdb on the master, then copy that to the slaves,
then run pg_upgrade on each of them. Obviously this needs some testing.

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

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