Feedback-ID: ia2694551:Fastmail
Date: Tue, 5 Mar 2024 08:34:18 +0100
From: 'Alvaro Herrera' <alvherre@alvh.no-ip.org>
To: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Some shared memory chunks are allocated even if related
 processes won't start
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On 2024-Mar-05, Hayato Kuroda (Fujitsu) wrote:

> Basically sounds good. My concerns are:
> 
> * GetNamedDSMSegment() does not returns a raw pointer to dsm_segment. This means
>   that it may be difficult to do dsm_unpin_segment on the caller side.

Maybe we don't need a "named" DSM segment at all, and instead just use
bare dsm segments (dsm_create and friends) or a DSA -- not sure.  But
see commit 31ae1638ce35, which removed use of a DSA in autovacuum/BRIN.
Maybe fixing this is just a matter of reverting that commit.  At the
time, there was a belief that DSA wasn't supported everywhere so we
couldn't use it for autovacuum workitem stuff, but I think our reliance
on DSA is now past the critical point.

BTW, we should turn BRIN autosummarization to be on by default.

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/
"Las mujeres son como hondas:  mientras más resistencia tienen,
 más lejos puedes llegar con ellas"  (Jonas Nightingale, Leap of Faith)