Re: TRAP: FailedAssertion("HaveRegisteredOrActiveSnapshot()", File: "toast_internals.c", Line: 670, PID: 19403)

At Wed, 30 Mar 2022 10:06:17 +0900 (JST), Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com> wrote in
> At Tue, 29 Mar 2022 13:29:15 +0200, Erik Rijkers <er(at)xs4all(dot)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