Date: Wed, 30 Mar 2022 11:46:13 +0900 (JST)
Message-Id: <20220330.114613.1177577626285014184.horikyota.ntt@gmail.com>
To: er@xs4all.nl
Cc: boekewurm+postgres@gmail.com, pgsql-hackers@lists.postgresql.org
Subject: Re: TRAP: FailedAssertion("HaveRegisteredOrActiveSnapshot()",
 File: "toast_internals.c", Line: 670, PID: 19403)
From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
In-Reply-To: <20220330.100617.1491348930290941094.horikyota.ntt@gmail.com>
References: 
 <CAEze2Wgv4FNYjjtY13HzgC+affAXsSVJYiztrN149B6+O+zq7Q@mail.gmail.com>
	<dbebe820-eec3-d643-aab7-26a33392c27b@xs4all.nl>
	<20220330.100617.1491348930290941094.horikyota.ntt@gmail.com>
User-Agent: Mew version 6.8 on Emacs 26.1
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Archived-At: 
 <https://www.postgresql.org/message-id/20220330.114613.1177577626285014184.horikyota.ntt%40gmail.com>
Precedence: bulk

At Wed, 30 Mar 2022 10:06:17 +0900 (JST), Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote in 
> At Tue, 29 Mar 2022 13:29:15 +0200, Erik Rijkers <er@xs4all.nl> wrote in 
> > Op 29-03-2022 om 12:50 schreef Matthias van de Meent:
> > > An shorter (?) reproducer might be the following, which forces any
> > > value for 'a' to be toasted and thus triggering the check in
> > > init_toast_snapshot regardless of value length:
> > > CREATE TABLE t (a text);
> > > ALTER TABLE t ALTER COLUMN a SET STORAGE EXTERNAL;
> > > INSERT INTO t VALUES ('toast');
> > > BEGIN;
> > > DECLARE c CURSOR FOR SELECT * FROM t;
> > > FETCH ALL IN c;
> 
> Yeah, unfortunately I tried that first and saw it didn't work. And it
> still doesn't for me.  With such a short text pg_detoast_datum_pakced
> doesn't call detoast_attr.  Actually it is VARATT_IS_1B. (@master)
> 
> I think I'm missing something here. I'm going to examine around.

Hmm. Strange. My memory tells that I did the same thing before.. I
thought that it is somewhat related to compression since repeat('x',
4096) didin't seem working at that time, but it worked this time.
Maybe I was confused between extended and external..

But, in the first place the *fix* has been found to be wrong.  I'm
going to search for the right fix..


regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center