Subject: Replication using patroni on different ubuntu os versions

From: OMPRAKASH SAHU <[email-masked]>
Date: Tue, 16 Sep 2025 12:48:14 +0530

Hi Team,

Greetings!!

I have 3 node patroni postgresql cluster in which primary and replica is
running on Ubuntu 20 and third one is running on Ubuntu 24 that is in DR
region.

So if we do the switch over on DR and then switch back to primary region,
is there any chance of data corruption due to OS version mismatch.

Postgresql version -16

Regards,
OM

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From: Ron Johnson <[email-masked]>
Date: Tue, 16 Sep 2025 03:34:40 -0400

> is there any chance of data corruption due to OS version mismatch.

The problem is that corruption in text indices can happen due to collation
changes from gnu libc version upgrades..

-- 
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> lobster!

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From: OMPRAKASH SAHU <[email-masked]>
Date: Tue, 16 Sep 2025 16:06:21 +0530

Hi @Ron,

What if collation is glibc independent i.e inbuilt C.UTF-8? still do we
have any chance of inconsistency?

Regards,
OM

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From: Ron Johnson <[email-masked]>
Date: Tue, 16 Sep 2025 09:55:20 -0400

Be like Project Farm, and test that. 😀  For example, insert records with
all sorts of non-ASCII characters (i.e. letters with diacritic marks, œ, æ,
other currency symbols etc) into  "SELECT text_fld FROM very_big_table_
ORDER BY text_fld" into a csv file on each server, and then take the md5sum.

Testing various regex predicates in WHERE clauses is also a good ise.

If they're not the same, well, you have your answer: it's a problem.  If
they _are_ the same, then *either* it's not a problem *or* your test data
is insufficient.

On Tue, Sep 16, 2025 at 6:36 AM OMPRAKASH SAHU <[email-masked]> wrote:

>>> So if we do the switch over on DR and then switch back to primary
>>> region, is there any chance of data corruption due to OS version mismatch.
>>>
>>
>> The problem is that corruption in text indices can happen due to
>> collation changes from gnu libc version upgrades..
>>
>

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From: Ron Johnson <[email-masked]>
Date: Tue, 16 Sep 2025 09:56:23 -0400

The bottom line is that it's not supported.  You're doing this your own
risk.