Re: Optimize LISTEN/NOTIFY

Joel Jacobson <joel@compiler.org>

From: "Joel Jacobson" <joel@compiler.org>

To: "Tom Lane" <tgl@sss.pgh.pa.us>

Cc: "Chao Li" <li.evan.chao@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2025-10-20T05:12:18Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Optimize LISTEN/NOTIFY via shared channel map and direct advancement.
- 282b1cde9ded 19 (unreleased) landed
Fix incorrect logic for caching ResultRelInfos for triggers
- 39dcfda2d23a 19 (unreleased) cited

Attachments

0002-optimize_listen_notify-v20-alt1-v2.txt (text/plain)

On Mon, Oct 20, 2025, at 00:10, Joel Jacobson wrote:
> Attachments:
> * 0001-optimize_listen_notify-v20.patch
> * 0002-optimize_listen_notify-v20.patch
> * 0002-optimize_listen_notify-v20-alt1.txt
> * 0002-optimize_listen_notify-v20-alt3.txt
> * 0002-optimize_listen_notify-v20-alt2.txt

Attaching a new alt1 version, that fixes the mistake of using max(pos,
advisoryPos) for lag calculation, which is wrong, since in alt1 it's the
backend itself that updates its 'pos' when it wakes up, and it's 'pos'
that asyncQueueAdvanceTail looks at, in alt1.

/Joel