Re: Major upgrade in patroni cluster

Hi Raj,

For a 3-node Patroni cluster with PostgreSQL 17.10, here is the high-level
approach I typically follow for a major version upgrade to 18.4 with
minimal downtime.High-Level Strategy

1. *Preparation & Testing*:
- *Staging Environment*: Perform the upgrade on a staging cluster
that mirrors your production setup. This is critical for validating
application compatibility and performance.
- *Release Notes*: Thoroughly review the release notes for PostgreSQL
18.4 to identify any breaking changes, deprecated features, or specific
collation/locale requirements that might impact your data.
- *Testing*: Validate your pgBackRest backups and ensure you can
restore from them before proceeding.
2. *Upgrade Execution (Minimal Downtime)*:
- *Rolling Upgrade*: Utilize Patroni’s rolling upgrade capability.
You can upgrade one replica at a time by stopping the Patroni service,
upgrading the PostgreSQL binaries, and restarting.
- *Switchover*: Once the replicas are upgraded, perform a controlled
switchover to promote an upgraded replica to leader. Finally, upgrade the
former leader.
- *pg_upgrade*: In many cases, you may need to use the
pg_upgrade utility.
If you use it, ensure you run it with the -k (link) option where
possible to significantly speed up the process and minimize downtime.
3. *Key Considerations*:
- *OS/Library Compatibility*: Since you are moving to a newer PG
version, ensure the underlying OS libraries (especially glibc) are
compatible, as this can affect collation.
- *PgBouncer/HAProxy*: Ensure your connection poolers and HA setup
are correctly updated to point to the new binary paths if the
installation
location changes.
- *Validation*: After the upgrade, run your application suite against
the cluster to catch any performance regressions.

Let me know if you’d like to discuss specific steps for the pg_upgrade process
or how to handle the replication configuration changes.

Best regards,

Mahesh Sathe

Sent from Gmail Mobile

On Sun, 28 Jun 2026 at 9:53 PM, Raj <rajeshkumar(dot)dba09(at)gmail(dot)com> wrote:

> Hi All,
>
> I have a three node PATRONI cluster with postgres 17.10 version with
> PGBACKREST, pgnouncer and haproxy.
>
> We would like to upgrade postgres 18.4 version.
>
> What are the high level steps with minimal downtime? Though I did some
> research already, would like to understand how it's been followed.
>