On Mon, May 16, 2016 at 8:52 PM, David Fetter <david@fetter.org> wrote:
> In light of the above, it is perfectly reasonable to require, at least
> temporarily, setting up duplicate storage, or another node.
>
> I am aware that some cases exist where this is not possible, but I
> don't think we should twist ourselves into pretzels to accommodate a
> tiny minority of our users, which my experience in the field leads me
> to believe is the case.
So, on the one hand, I agree that logical replication is a great way
to facilitate major version upgrades. On the other hand, I think it's
completely wrong to suppose that only a tiny minority of people can't
use it. In some cases, hardware availability is definitely an issue.
But even when people have the hardware, being able to cleanly do a
cutover from one master to another is not necessarily something people
are set up to do. Getting that to work well requires more brainpower
than many users are willing to give to their database. A lot of
people want to just shut the database down, upgrade it, and start it
back up.
pg_upgrade does that, kinda. I'd like to have something better, but
in the absence of that, I think it's quite wrong to think about
deprecating it, even if we had logical replication fully integrated
into core today. Which we by no means do.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company