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* BUG #19051: Is it possible to move a TOAST table to a different tablespace than its parent table?
@ 2025-09-14 09:17 PG Bug reporting form <noreply@postgresql.org>
0 siblings, 1 reply; 2+ messages in thread
From: PG Bug reporting form @ 2025-09-14 09:17 UTC (permalink / raw)
To: pgsql-bugs@lists.postgresql.org; +Cc: mhararci@gmail.com
The following bug has been logged on the website:
Bug reference: 19051
Logged by: Mustafa HARARCI
Email address: mhararci@gmail.com
PostgreSQL version: 16.10
Operating system: Ubuntu 16.10-1.pgdg22.04+1
Description:
Hello everyone,
I'm currently using PostgreSQL 16.10 and I've run into a challenge regarding
moving TOAST data for a table. My goal is to have the TOAST data for a
column stored in a different tablespace from the parent table.
Specifically, I have a users table with a profile_data column of type JSONB,
which can contain large objects. I want the users table itself to reside in
the ts_medium_data tablespace, while its associated TOAST data is stored in
a separate ts_medium_toast tablespace.
I've attempted the following steps:
I created the users table in the ts_medium_data tablespace.
I identified the associated TOAST table using the pg_class catalog (SELECT
reltoastrelid::regclass FROM pg_class WHERE relname = 'users';), which
returned an object like pg_toast.pg_toast_16646.
As a superuser (postgres), I tried to move the TOAST table to the new
tablespace using ALTER TABLE pg_toast.pg_toast_16646 SET TABLESPACE
ts_medium_toast;.
This command, however, resulted in the following error: ERROR: permission
denied: "pg_toast_16646" is a system catalog.
This error suggests that direct modification of the TOAST table is not
allowed, even with superuser privileges.
My question is, is it fundamentally possible in PostgreSQL to store a
table's main data and its TOAST data in different tablespaces? Is this
behavior a design constraint? If so, is there any workaround for this, or is
this simply not a supported feature?
Any insight into this behavior or guidance on a potential solution would be
greatly appreciated.
Thank you.
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: BUG #19051: Is it possible to move a TOAST table to a different tablespace than its parent table?
@ 2025-09-14 10:29 Laurenz Albe <laurenz.albe@cybertec.at>
parent: PG Bug reporting form <noreply@postgresql.org>
0 siblings, 0 replies; 2+ messages in thread
From: Laurenz Albe @ 2025-09-14 10:29 UTC (permalink / raw)
To: mhararci@gmail.com; pgsql-bugs@lists.postgresql.org
On Sun, 2025-09-14 at 09:17 +0000, PG Bug reporting form wrote:
> I'm currently using PostgreSQL 16.10 and I've run into a challenge regarding
> moving TOAST data for a table. My goal is to have the TOAST data for a
> column stored in a different tablespace from the parent table.
>
> Specifically, I have a users table with a profile_data column of type JSONB,
> which can contain large objects. I want the users table itself to reside in
> the ts_medium_data tablespace, while its associated TOAST data is stored in
> a separate ts_medium_toast tablespace.
Don't write to the bugs mailing list if you need help.
I have directed replies to the -general mailing list.
You won't be able to put a table and its TOAST table into different tablespaces.
But there wouldn't be any benefit in doing that anyway, so that
is no problem. Perhaps you could detail the *real problem* you are trying
to solve...
Yours,
Laurenz Albe
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2025-09-14 09:17 BUG #19051: Is it possible to move a TOAST table to a different tablespace than its parent table? PG Bug reporting form <noreply@postgresql.org>
2025-09-14 10:29 ` Laurenz Albe <laurenz.albe@cybertec.at>
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