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From: Ron Johnson <ronljohnsonjr@gmail.com>
Date: Thu, 12 Jun 2025 09:18:52 -0400
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Subject: Re: PostgreSQL Upgrade (v9.5 to v12) with Django 2.0
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On Thu, Jun 12, 2025 at 7:30=E2=80=AFAM Kushal Shri <shrikushalk@gmail.com>=
 wrote:

> Dear Community,
>
> We are in the process of planning a PostgreSQL upgrade and would greatly
> appreciate any insights, best practices, or lessons learned from your
> experiences.
>
> Current Setup:
>    - PostgreSQL version: 9.5
>    - Django version: 2.0
>    - Database size: ~3 TB
>    - One Master 4 Replicas(Streaming Replication)
>
> We are taking a phased approach to this upgrade. In Phase 1, our goal is
> to upgrade PostgreSQL from v9.5 to v12, ensuring compatibility with our
> current Django 2.0 application.
>
> As part of this, I would like to understand:
>
> - What is the highest PostgreSQL version reliably supported with Django
> 2.0?
> - What upgrade strategies or methods have worked well for you in similar
> environments?
> - Any gotchas or performance considerations to keep in mind with large
> databases during such upgrades?
>
> Your recommendations and experiences will be extremely valuable in helpin=
g
> us plan and execute this upgrade smoothly.
>

If you have (or can add) 3-4TB on your existing server, then pg_upgrade to
12.22 is possible.  (You can also do a hard-links pg_upgrade, but there's
no going back once you start the instance with v12.  That's why I like
upgrading to a new disk.)  A 3TB instance should take no more than a few
hours (depending on disk and controller speed.)