Horton

Re: Correcting freeze conflict horizon calculation

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Andres Freund <andres@anarazel.de>, Heikki Linnakangas <hlinnaka@iki.fi>
Date: 2025-06-02T19:49:06Z
Lists: pgsql-hackers 
On Mon, Jun 2, 2025 at 3:40 PM Melanie Plageman
<melanieplageman@gmail.com> wrote:
> Oh, and, more specifically, in my previous email, I was wondering if,
> and why, in 16 this diff wouldn't be correct

I *think* that it would be correct.

Again, it is certainly possible to make the conflict horizon precisely
the oldest safe value in all cases. How much that actually buys you
seems much less clear.

-- 
Peter Geoghegan

Commits

  1. Use the newest to-be-frozen xid as the conflict horizon for freezing

  2. Avoid hot standby cancels from VAC FREEZE