Re: Optimize LISTEN/NOTIFY

On Mon, Oct 27, 2025, at 02:27, Chao Li wrote:
>> On Oct 27, 2025, at 07:24, Joel Jacobson <joel(at)compiler(dot)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