Message-ID: <ed232cb7-1fdc-415a-92e6-8df908ce6128@iki.fi>
Date: Wed, 3 Dec 2025 21:12:40 +0200
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Subject: Re: POC: make mxidoff 64 bits
To: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>,
 Maxim Orlov <orlovmg@gmail.com>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>,
 Alexander Korotkov <aekorotkov@gmail.com>, wenhui qiu
 <qiuwenhuifx@gmail.com>,
 Postgres hackers <pgsql-hackers@lists.postgresql.org>
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From: Heikki Linnakangas <hlinnaka@iki.fi>
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On 01/12/2025 14:35, Ashutosh Bapat wrote:
> On Mon, Dec 1, 2025 at 2:23 PM Maxim Orlov <orlovmg@gmail.com> wrote:
>> On Fri, 28 Nov 2025 at 16:17, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> wrote:
>>> An UPDATE waits for FOR SHARE query to finish, and vice versa. In my
>>> experiments I didn't see an UPDATE creating a multi-xact. Why do we
>>> have UPDATEs in the load created by the test? Am I missing something?
>>
>> As far as I remember, this was done on purpose to create different
>> multixact members statuses randomly.
> 
> In that case, better to include that in the comments.

I think that was indeed the purpose, but the test should use FOR KEY 
SHARE rather than FOR SHARE. Otherwise the UPDATEs don't generate multixids.

- Heikki