Re: pg_upgrade and rsync

On Wed, Jan 28, 2015 at 09:26:11PM -0800, Josh Berkus wrote:
>
> > So, for my 2c, I'm on the fence about it.  On the one hand, I agree,
> > it's a bit of a complex process to get right.  On the other hand, it's
> > far better if we put something out there along the lines of "if you
> > really want to, this is how to do it" than having folks try to fumble
> > through to find the correct steps themselves.
>
> So, here's the correct steps for Bruce, because his current doc does not
> cover all of these.  I really think this should go in as a numbered set
> of steps; the current doc has some steps as steps, and other stuff
> buried in paragraphs.
>
> 1. Install the new version binaries on both servers, alongside the old
> version.
>
> 2. If not done by the package install, initdb the new version's data
> directory.
>
> 3. Check that the replica is not very lagged.  If it is, wait for
> traffic to die down and for it to catch up.

Now that 9.4.1 is released, I would like to get this doc patch applied
--- it will close the often-requested feature of how to pg_upgrade slave
clusters.

I wasn't happy with Josh's specification above that the "replica is not
very lagged", so I added a bullet point to check the pg_controldata
output to verify that the primary and standby servers are synchronized.

Yes, this adds even more complication to the pg_upgrade instructions,
but it is really more of the same complexity.  pg_upgrade really needs
an install-aware and OS-aware tool on top of it to automate much of
this.

Patch attached.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + Everyone has their own god. +