Date: Thu, 4 Feb 2021 14:36:37 -0300
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Julien Rouhaud <rjuju123@gmail.com>
Cc: Mahendra Singh Thalor <mahi6run@gmail.com>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Faulty HEAP_XMAX_LOCK_ONLY & HEAP_KEYS_UPDATED hintbit
 combination
Message-ID: <20210204173637.GA30985@alvherre.pgsql>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20210204163750.GB22612@nol>
User-Agent: Mutt/1.10.1 (2018-07-13)
Precedence: bulk

On 2021-Feb-05, Julien Rouhaud wrote:

> Thanks, that's way better, copied in v3.  I'm still a bit worried about that
> description though, as that flag isn't consistently set for the FOR UPDATE
> case.  Well, to be more precise it's maybe consistently set when the hint bits
> are computed, but in some cases the flag is later cleared, so you won't
> reliably find it in the tuple.

Hmm, that sounds bogus.  I think the resetting of the other bits should
be undone afterwards, but I'm not sure that we correctly set
KEYS_UPDATED again after the TOAST business.  (What stuff does, from
memory, is to make the tuple look as if it is fully updated, which is
necessary during the TOAST handling; if the bits are not correctly set
transiently, that's okay.  But it needs reinstated again later, once the
TOAST stuff is finished).

-- 
Álvaro Herrera                            39°49'30"S 73°17'W
"El número de instalaciones de UNIX se ha elevado a 10,
y se espera que este número aumente" (UPM, 1972)