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From: Joel Jacobson <[email protected]>
To: Tom Lane <[email protected]>
To: Arseniy Mukhin <[email protected]>
Cc: pgsql-hackers <[email protected]>
Subject: Re: Optimize LISTEN/NOTIFY
Date: Wed, 15 Oct 2025 23:10:47 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
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On Wed, Oct 15, 2025, at 16:16, Tom Lane wrote:
> I think we can perhaps salvage the idea if we invent a separate
> "advisory" queue position field, which tells its backend "hey,
> you could skip as far as here if you want", but is not used for
> purposes of SLRU truncation. 

I want to experiment with this idea too.

I assume the separate "advisory" queue position field
would actually need to be two struct fields, since a queue position
consists of a page and an offset, right?

   typedef struct QueuePosition
   {
     int64		page;			/* SLRU page number */
     int			offset;			/* byte offset within page */
+    int64		advisoryPage;	/* suggested skip-ahead page */
+    int			advisoryOffset;	/* suggested skip-ahead offset */
   } QueuePosition;

Or would we want rather want a single "advisory" field that would also
be of type QueuePosition?

/Joel

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