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Message-ID: <b009d07a-e271-4eba-804c-d6a6b86dcc64@gmail.com>
Date: Tue, 8 Sep 2026 18:33:18 +0200
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Subject: Re: Add pg_stat_vfdcache view for VFD cache statistics
To: Ayoub Kazar <kazarayoub2004@gmail.com>
Cc: KAZAR Ayoub <ma_kazar@esi.dz>, Tomas Vondra <tomas@vondra.me>,
 Jakub Wartak <jakub.wartak@enterprisedb.com>,
 Pg Hackers <pgsql-hackers@postgresql.org>
References: 
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 <42776281-3603-4161-b47d-d4ffd2029e8c@vondra.me>
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 <02cfc5e7-e152-4d2d-8b4b-e899d9901ed5@gmail.com>
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 <3b394e5f-ac4e-446c-b422-92be2b984722@gmail.com>
 <CADu+CpSY57xpQsGr1CAESUHxGv_Y3_aABmkHC-Gh9GpEG3tpPw@mail.gmail.com>
Content-Language: en-US
From: David Geier <geidav.pg@gmail.com>
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>>>> However, I'm wondering if the better approach wouldn't be to change fd.c
>>>> to use a long-lived memory context. Then all bookkeeping would happen
>>>> automatically and the memory size could simply be reported via existing
>>>> memory context stats infrastructure.
>>>>
>>>> Not entirely sure though if there's some roadblock when switching to a
>>>> memory context.
>>> I don't see any issue with this either. However, the only benefit we
>> would
>>> gain is using existing infrastructure but only for backend vfd cache
>> memory
>>> (i.e cache_bytes).
>>> Everything else stays the same (counters, cluster-wide memory);
>> therefore,
>>> if there's no other benefit to replacing with memory contexts, maybe it's
>>> not worth it.
>>
>> The biggest benefit in my view is consistency with the rest of PostgreSQL.
>> That is from a usage point of view as well as from a coding point of view.
>> If you want, I can give that a try and share a patch with you if
>> successful.
>>
> Yes of course, I’d be happy to take a look.
Attached is the patch. It's pretty small and passes regress tests.

--
David Geier
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