Date: Sat, 11 Nov 2017 12:26:35 +0100
From: Johannes Truschnigg <johannes@truschnigg.info>
To: Debraj Manna <subharaj.manna@gmail.com>
Cc: pgsql-admin@postgresql.org
Subject: Re: Upgrading postgres to 10 from 9.5 using pg_upgradecluster
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Hi!

On Sat, Nov 11, 2017 at 08:02:19AM +0530, Debraj Manna wrote:
> I am testing the process of upgrading postgres to 10 from 9.5
>=20
> [...]
>=20
> Can someone let me know the following
>=20
>    1. If there is a way I can check if the upgrade will be successful
>    before going for the actual upgrade?

Before doing a release upgrade, we usually restore the latest backup of the
cluster that's going to be upgraded to another host, and perform the planned
upgrade procedure there. For the actual upgrade, we schedule a maintenance
window, and repeaet the steps recorded during the successful test-run. This
has the added benefit that you can have confidence in your recovery/restore
process in case something goes awry.

There's no other way I know of that "simulates" performing the actual upgra=
de
(pg_upgrade does some pre-flight checking before it actually starts doing
work, but errors can still arise after the point of no return - which in
"link" mode means that you'll have two broken clusters, and will have to
restore from backup).


>    2. If I am using the link option in the upgrade can I still use the su=
do
>    pg_dropcluster 9.5 main?

Yes.


It's a very good idea to gather experience with the workflow in a test setu=
p,
just like you seem to be doing. You'll see that the procedure and tooling
around upgrades is very robust - but with database administration, nothing
beats a combination of diligent planning, carefulness, and experience.

--=20
with best regards:
- Johannes Truschnigg ( johannes@truschnigg.info )

www:   https://johannes.truschnigg.info/
phone: +43 650 2 133337
xmpp:  johannes@truschnigg.info

Please do not bother me with HTML-email or attachments. Thank you.

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