Re: Upgrade and re-synchronization with logical replication(pglogical and PG 10)

> On Jan 23, 2018, at 9:36 AM, Peter Eisentraut <peter.eisentraut@2ndquadrant.com> wrote:
>
> On 1/22/18 01:53, Chad Trabant wrote:
>> 1) In my initial testing it seems that an upgrade via pg_upgrade does
>> not migrate logical replication slots or origins
>> (pg_replication_slots and pg_replication_origin).
>
> Correct.

Thank you for confirming.  I'm sure there is a good reason for this, can someone explain why (even if briefly)?

> A better approach might be to use pglogical itself to do the upgrade.
> That is, set up a new replica somewhere that is PG10, replicate into
> that, and switch over.

This requires duplicating the data and host.  What I'm trying to do is upgrade an existing publisher and subscriber
pairwith limited downtime. I suppose this could be done by replicating the publisher to a new publisher, then to a new
subscriber,then swap out the old systems for the new.  Unfortunately, I have have some systems with a large volume of
dataand specialized hardware (relative to our data center), which makes creating a duplicate not possible. 

Luckily in my scenario it is acceptable to turn off all inserts/updates/deletes/truncates to the paired systems for
shortterm, planned maintenance and only one of each pair needs to be up for select access.  I'll be experimenting with
howto re-attach a publisher-subscriber pair post-pg_upgrade.  Any hints or gotchas that could guide me would be
appreciated.