Message-ID: <c60b0558-290b-4fe8-b839-6a7725c980b3@joeconway.com>
Date: Wed, 12 Mar 2025 22:55:11 -0400
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Subject: Re: Moving from Linux to Linux?
To: Paul Foerster <paul.foerster@gmail.com>,
 Adrian Klaver <adrian.klaver@aklaver.com>
Cc: Pgsql-General List <pgsql-general@lists.postgresql.org>
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From: Joe Conway <mail@joeconway.com>
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On 3/12/25 16:55, Paul Foerster wrote:
> Hi Adrian,
> 
>> On 12 Mar 2025, at 21:26, Adrian Klaver <adrian.klaver@aklaver.com> wrote:
>> 
>> A good summary of the glibc issue:
>> 
>> https://wiki.postgresql.org/wiki/Locale_data_changes
>> 
>> With distro information:
>> 
>> https://wiki.postgresql.org/wiki/Locale_data_changes#What_Linux_distributions_are_affected
> 
> I know the article, thanks. We needed a full reindex when upgrading from SLES 15.2 to 15.3. We're on 15.5 now, partly already on 15.6. Thank god, we didn't have that ugly database back then that we have now. But I see the next doomsday coming on the horizon. 🤣
> 
> Also, we try to get rid of the libc locale provider and switch to libicu, wherever possible.

If you are desperate you could start with 
https://github.com/awslabs/compat-collation-for-glibc and create a new 
branch for your current version of SLES/glibc and deploy the resulting 
rpm to RHEL. At least in theory. FWIW I was able to get the glibc locale 
compatibility library for AL2 (glibc 2.26) to work fine on Linux Mint 
system (glibc 2.34).

For more on the compatibility library you could watch a presentation[1] 
starting here:
   https://youtu.be/0E6O-V8Jato?t=1749

The other option, which may be equally untenable, is to upgrade in-place 
to pg17 and convert everything to use the new built-in collation 
provider. That ought to be portable across different versions of Linux.

The problem you might find with libicu is that different versions of ICU 
can have the same issues as different versions of glibc, and you might 
not have the same ICU version available on SLES and RHEL.

If you want to explore the compatibility library approach contact me off 
list and I will try to get you started. It has been a couple of years 
since I touched it, but when I did it took me a couple of days to get 
from the AL2 (glibc 2.26) branch (which was done first) to the RHEL 7 
(glibc 2.17) branch.

HTH,

[1] https://www.joeconway.com/presentations/2025-PGConf.IN-glibc.pdf

-- 
Joe Conway
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com