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Date: Mon, 27 Oct 2025 07:18:37 +0100
From: "Joel Jacobson" <joel@compiler.org>
To: pgsql-hackers <pgsql-hackers@postgresql.org>
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Subject: Re: Optimize LISTEN/NOTIFY
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On Mon, Oct 27, 2025, at 02:27, Chao Li wrote:
>> On Oct 27, 2025, at 07:24, Joel Jacobson <joel@compiler.org> wrote:
>>=20
>> Write-up of changes since v20:
>>=20
>> Two new fields have been added to QueueBackendStatus:
>> + QueuePosition advisoryPos; /* safe skip-ahead position */
>> + bool advancingPos; /* backend is reading the queue */
...
> I did a quick review on v21 only focusing on the =E2=80=9Cdirect advan=
cement=E2=80=9D logic.
>
> In v21, you added advisoryPos and advancingPos which is same as my=20
> proposed solution. But you missed an important point from mine.
>
...
> From this perspective, we need to add a new field=20
> adviancingTillPos to QueueBackendStatus. (This field was also missing=20
> from my proposed patch).

I'm doubtful yet another field is worth the added complexity cost.

Before increasing the complexity further, I think we should first
try to simulate somewhat realistic workloads, to see if we actually
have a problem first.

/Joel