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Date: Fri, 6 Feb 2026 09:12:20 -0500
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Subject: Re: [PING] fallocate() causes btrfs to never compress postgresql
 files
To: Thomas Munro <thomas.munro@gmail.com>,
 Jakub Wartak <jakub.wartak@enterprisedb.com>
Cc: Bruce Momjian <bruce@momjian.us>, Dimitrios Apostolou <jimis@gmx.net>,
 Magnus Hagander <magnus@hagander.net>, Tomas Vondra <tomas@vondra.me>,
 pgsql-hackers@lists.postgresql.org, Andres Freund <andres@anarazel.de>,
 Melanie Plageman <melanieplageman@gmail.com>,
 Heikki Linnakangas <hlinnaka@iki.fi>,
 Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
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From: Andrew Dunstan <andrew@dunslane.net>
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On 2026-02-06 Fr 3:29 AM, Thomas Munro wrote:
> On Fri, Feb 6, 2026 at 8:19 PM Jakub Wartak
> <jakub.wartak@enterprisedb.com> wrote:
>> On Fri, Feb 6, 2026 at 6:12 AM Thomas Munro <thomas.munro@gmail.com> wrote:
>>> On Mon, Jan 12, 2026 at 11:04 PM Jakub Wartak
>>> <jakub.wartak@enterprisedb.com> wrote:
>>>>>> I'm proposing to back-patch 0001.  0002 and 0003 are proposals for master only.
>>>> Do you have any plans to commit this before February (before next
>>>> minor release) or perhaps do you need some further input or help in
>>>> this $thread? (I'm mainly after the XFS thingy, but we kill two birds
>>>> with 1 stone here).
>>> Pushed.
>> Thank You very much !
> BTW the rest of the patches will reemerge for master, but for the
> minimal one back-patched: crake complains about an ABI break due to
> GUC table changes.  Of course adding a GUC to the stable branches is
> unusual and we discussed the need for it in this case.  Is that
> expected?  In what way is it part of the ABI?  How would one determine
> in advance that the ABI checker will complain?
>
>

First, thanks for committing this.

How to tell it will detect a break is a good question. I guess a trivial 
answer would be to run the buildfarm client with the ABICompCheck module 
enabled, but that's probably a big ask if you're not set up for it. This 
one is relatively hard to catch because tthe ABI change is in a 
generated file, so the triggering source change isn't even in the 
include directory.

Not sure if we want to start using a suppressions file to exclude 
certain symbols from consideration. They are described here 
https://man7.org/linux/man-pages/man7/libabigail.7.html


cheers


andrew


--
Andrew Dunstan
EDB: https://www.enterprisedb.com