pg.ddx.io pgsql-bugs@postgresql.org mailing list archive
help / color / mirror / Atom feedBUG #17669: Invalid TOAST pointer in PL/pgSQL variable
3+ messages / 3 participants
[nested] [flat]
* BUG #17669: Invalid TOAST pointer in PL/pgSQL variable
@ 2022-10-27 19:45 PG Bug reporting form <noreply@postgresql.org>
2022-10-28 13:43 ` Re: BUG #17669: Invalid TOAST pointer in PL/pgSQL variable Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 1 reply; 3+ messages in thread
From: PG Bug reporting form @ 2022-10-27 19:45 UTC (permalink / raw)
To: pgsql-bugs@lists.postgresql.org; +Cc: s.shinderuk@postgrespro.ru
The following bug has been logged on the website:
Bug reference: 17669
Logged by: Sergey Shinderuk
Email address: s.shinderuk@postgrespro.ru
PostgreSQL version: 15.0
Operating system: Ubuntu 22.04
Description:
Is it a bug or a known limitation?
create table t (a int, b text);
alter table t alter column b set storage external;
insert into t values (1, repeat('a',3000));
create function f() returns text as $$
declare
s text;
begin
select b into s from t where a = 1;
truncate t;
return s;
end;
$$ language plpgsql;
postgres=# select f();
ERROR: missing chunk number 0 for toast value 24727 in pg_toast_24722
If I replace "truncate" with "drop table", then I get:
ERROR: could not open relation with OID 24725
With "delete from t" it just works.
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: BUG #17669: Invalid TOAST pointer in PL/pgSQL variable
2022-10-27 19:45 BUG #17669: Invalid TOAST pointer in PL/pgSQL variable PG Bug reporting form <noreply@postgresql.org>
@ 2022-10-28 13:43 ` Tom Lane <tgl@sss.pgh.pa.us>
2022-10-28 14:16 ` Re: BUG #17669: Invalid TOAST pointer in PL/pgSQL variable Sergey Shinderuk <s.shinderuk@postgrespro.ru>
0 siblings, 1 reply; 3+ messages in thread
From: Tom Lane @ 2022-10-28 13:43 UTC (permalink / raw)
To: s.shinderuk@postgrespro.ru; +Cc: pgsql-bugs@lists.postgresql.org
PG Bug reporting form <noreply@postgresql.org> writes:
> create function f() returns text as $$
> declare
> s text;
> begin
> select b into s from t where a = 1;
> truncate t;
> return s;
> end;
> $$ language plpgsql;
> postgres=# select f();
> ERROR: missing chunk number 0 for toast value 24727 in pg_toast_24722
To prevent that, every fetch into a plpgsql variable would have
to immediately detoast the value, in case somebody did something
as weird as dropping/truncating the table later in the function.
That's an awfully expensive bit of protection. We do in fact
do it like that in procedures (more specifically, in non-atomic
contexts), so a possible workaround for you is to make this a
procedure not a function. I'm disinclined to change it otherwise.
regards, tom lane
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: BUG #17669: Invalid TOAST pointer in PL/pgSQL variable
2022-10-27 19:45 BUG #17669: Invalid TOAST pointer in PL/pgSQL variable PG Bug reporting form <noreply@postgresql.org>
2022-10-28 13:43 ` Re: BUG #17669: Invalid TOAST pointer in PL/pgSQL variable Tom Lane <tgl@sss.pgh.pa.us>
@ 2022-10-28 14:16 ` Sergey Shinderuk <s.shinderuk@postgrespro.ru>
0 siblings, 0 replies; 3+ messages in thread
From: Sergey Shinderuk @ 2022-10-28 14:16 UTC (permalink / raw)
To: Tom Lane <tgl@sss.pgh.pa.us>; +Cc: pgsql-bugs@lists.postgresql.org
On 28.10.2022 16:43, Tom Lane wrote:
> PG Bug reporting form <noreply@postgresql.org> writes:
>> postgres=# select f();
>> ERROR: missing chunk number 0 for toast value 24727 in pg_toast_24722
>
> To prevent that, every fetch into a plpgsql variable would have
> to immediately detoast the value, in case somebody did something
> as weird as dropping/truncating the table later in the function.
> That's an awfully expensive bit of protection. We do in fact
> do it like that in procedures (more specifically, in non-atomic
> contexts), so a possible workaround for you is to make this a
> procedure not a function. I'm disinclined to change it otherwise.
Thank you for explaining.
--
Sergey Shinderuk https://postgrespro.com/
^ permalink raw reply [nested|flat] 3+ messages in thread
end of thread, other threads:[~2022-10-28 14:16 UTC | newest]
Thread overview: 3+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2022-10-27 19:45 BUG #17669: Invalid TOAST pointer in PL/pgSQL variable PG Bug reporting form <noreply@postgresql.org>
2022-10-28 13:43 ` Tom Lane <tgl@sss.pgh.pa.us>
2022-10-28 14:16 ` Sergey Shinderuk <s.shinderuk@postgrespro.ru>
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox