From: Tom Lane <tgl@sss.pgh.pa.us>
To: "Joel Jacobson" <joel@compiler.org>
cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Optimize LISTEN/NOTIFY
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Comments: In-reply-to "Joel Jacobson" <joel@compiler.org>
	message dated "Sun, 13 Jul 2025 00:35:21 +0200"
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Date: Sat, 12 Jul 2025 19:18:40 -0400
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"Joel Jacobson" <joel@compiler.org> writes:
> The attached proof-of-concept patch proposes a straightforward
> optimization for the single-listener case. It introduces a shared-memory
> hash table mapping (dboid, channelname) to the ProcNumber of a single
> listener.

What does that do to the cost and parallelizability of LISTEN/UNLISTEN?

> The patch also includes a "wake only tail" optimization (contributed by
> Marko Tikkaja) to help prevent backends from falling too far behind.

Coulda sworn we dealt with that case some years ago.  In any case,
if it's independent of the other idea it should probably get its
own thread.

			regards, tom lane