Re: PostgreSQL Upgrade (v9.5 to v12) with Django 2.0

On Wed, 2025-06-11 at 16:39 +0545, Kushal Shri wrote:
> 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.

That's already wrong.  PostgreSQL v12 is out of support.  Upgrade to v17 or v18.

> As part of this, I would like to understand:
>
> - What is the highest PostgreSQL version reliably supported with Django 2.0?

You'll have to ask Django what they support.

> - What upgrade strategies or methods have worked well for you in similar environments?

pg_upgrade --link

> - Any gotchas or performance considerations to keep in mind with large databases
>   during such upgrades?

Make sure you don't have millions of Large Objects, otherwise the upgrade
will be very slow and memory consuming.

Yours,
Laurenz Albe