Re: Optimize LISTEN/NOTIFY - Mailing list pgsql-hackers

From Joel Jacobson
Subject Re: Optimize LISTEN/NOTIFY
Date
Msg-id 4b7b49a5-5e1a-44a8-93e0-60457d15cb1d@app.fastmail.com
Whole thread Raw
In response to Re: Optimize LISTEN/NOTIFY  (Chao Li <li.evan.chao@gmail.com>)
Responses Re: Optimize LISTEN/NOTIFY
List pgsql-hackers
On Mon, Oct 27, 2025, at 02:27, Chao Li wrote:
>> On Oct 27, 2025, at 07:24, Joel Jacobson <joel@compiler.org> wrote:
>>
>> Write-up of changes since v20:
>>
>> 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 “direct advancement” logic.
>
> In v21, you added advisoryPos and advancingPos which is same as my
> proposed solution. But you missed an important point from mine.
>
...
> From this perspective, we need to add a new field
> adviancingTillPos to QueueBackendStatus. (This field was also missing
> 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



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