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From: Mahesh Sathe <maheshsathe1@gmail.com>
Date: Mon, 6 Jul 2026 16:06:13 +0530
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 <CAG6Sa9Uz9_WTq7u2Zm6VJaJDvYh-vVbqbwstvARj6CJ7f3EGew@mail.gmail.com>
Subject: Re: Major upgrade in patroni cluster
To: Raj <rajeshkumar.dba09@gmail.com>
Cc: Pgsql-admin <pgsql-admin@lists.postgresql.org>
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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 specif=
ic
      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=E2=80=99s rolling upgrade capabi=
lity.
      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=E2=80=99d like to discuss specific steps for the pg_upgr=
ade 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=E2=80=AFPM, Raj <rajeshkumar.dba09@gmail.com> w=
rote:

> 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.
>

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<div>Hi Raj,<br><br>For a 3-node Patroni cluster with PostgreSQL 17.10, her=
e is the high-level approach I typically follow for a major version upgrade=
 to 18.4 with minimal downtime.High-Level Strategy<ol><li><b>Preparation &a=
mp; Testing</b>:<ul><li><b>Staging Environment</b>: Perform the upgrade on =
a staging cluster that mirrors your production setup. This is critical for =
validating application compatibility and performance.</li><li><b>Release No=
tes</b>: Thoroughly review the release notes for PostgreSQL 18.4 to identif=
y any breaking changes, deprecated features, or specific collation/locale r=
equirements that might impact your data.</li><li><b>Testing</b>: Validate y=
our <code>pgBackRest</code>=C2=A0backups and ensure you can restore from th=
em before proceeding.</li></ul></li><li><b>Upgrade Execution (Minimal Downt=
ime)</b>:<ul><li><b>Rolling Upgrade</b>: Utilize Patroni=E2=80=99s rolling =
upgrade capability. You can upgrade one replica at a time by stopping the P=
atroni service, upgrading the PostgreSQL binaries, and restarting.</li><li>=
<b>Switchover</b>: Once the replicas are upgraded, perform a controlled swi=
tchover to promote an upgraded replica to leader. Finally, upgrade the form=
er leader.</li><li><b><code>pg_upgrade</code></b>: In many cases, you may n=
eed to use the <code>pg_upgrade</code>=C2=A0utility. If you use it, ensure =
you run it with the <code>-k</code>=C2=A0(link) option where possible to si=
gnificantly speed up the process and minimize downtime.</li></ul></li><li><=
b>Key Considerations</b>:<ul><li><b>OS/Library Compatibility</b>: Since you=
 are moving to a newer PG version, ensure the underlying OS libraries (espe=
cially glibc) are compatible, as this can affect collation.</li><li><b>PgBo=
uncer/HAProxy</b>: Ensure your connection poolers and HA setup are correctl=
y updated to point to the new binary paths if the installation location cha=
nges.</li><li><b>Validation</b>: After the upgrade, run your application su=
ite against the cluster to catch any performance regressions.</li></ul></li=
></ol>Let me know if you=E2=80=99d like to discuss specific steps for the <=
code>pg_upgrade</code>=C2=A0process or how to handle the replication config=
uration changes.<br><br>Best regards,<br><br>Mahesh Sathe</div><div><br cle=
ar=3D"all"><br clear=3D"all"><div><div dir=3D"ltr" class=3D"gmail_signature=
" data-smartmail=3D"gmail_signature">Sent from Gmail Mobile</div></div></di=
v><div><br><div class=3D"gmail_quote gmail_quote_container"><div dir=3D"ltr=
" class=3D"gmail_attr">On Sun, 28 Jun 2026 at 9:53=E2=80=AFPM, Raj &lt;<a h=
ref=3D"mailto:rajeshkumar.dba09@gmail.com">rajeshkumar.dba09@gmail.com</a>&=
gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0=
 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir=3D"auto">Hi All=
,<div dir=3D"auto"><br></div><div dir=3D"auto">I have a three node PATRONI =
cluster with postgres 17.10 version with PGBACKREST, pgnouncer and haproxy.=
=C2=A0</div><div dir=3D"auto"><br></div><div dir=3D"auto">We would like to =
upgrade postgres 18.4 version.=C2=A0</div><div dir=3D"auto"><br></div><div =
dir=3D"auto">What are the high level steps with minimal downtime? Though I =
did some research already, would like to understand how it&#39;s been follo=
wed.</div></div>
</blockquote></div></div>

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