Re: Allow table AMs to define their own reloptions

On Thu, 4 Jun 2026 at 04:32, Andrew Dunstan <andrew(at)dunslane(dot)net> wrote:

>
> On 2025-05-26 Mo 7:06 AM, Julien Tachoires wrote:
> > On Sat, Mar 29, 2025 at 08:46:01AM +0100, Julien Tachoires wrote:
> >> On Sun, Mar 02, 2025 at 02:23:54PM +0100, Julien Tachoires wrote:
> >>> On Sun, Mar 02, 2025 at 09:56:41AM +0100, Julien Tachoires wrote:
> >>>> With the help of the new TAM routine 'relation_options', table access
> >>>> methods can with this patch define their own reloptions
> >>>> parser/validator.
> >>>>
> >>>> These reloptions can be set via the following commands:
> >>>> 1. CREATE TABLE ... USING table_am
> >>>> WITH (option1='value1', option2='value2');
> >>>> 2. ALTER TABLE ...
> >>>> SET (option1 'value1', option2 'value2');
> >>>> 3. ALTER TABLE ... SET ACCESS METHOD table_am
> >>>> OPTIONS (option1 'value1', option2 'value2');
> >>>>
> >>>> When changing table's access method, the settings inherited from the
> >>>> former TAM can be dropped (if not supported by the new TAM) via: DROP
> >>>> option, or, updated via: SET option 'value'.
> >>>>
> >>>> Currently, tables using different TAMs than heap are able to use
> heap's
> >>>> reloptions (fillfactor, toast_tuple_target, etc...). With this patch
> >>>> applied, this is not the case anymore: if the TAM needs to have access
> >>>> to similar settings to heap ones, they have to explicitly define them.
> >>>>
> >>>> The 2nd patch file includes a new test module 'dummy_table_am' which
> >>>> implements a dummy table access method utilized to exercise TAM
> >>>> reloptions. This test module is strongly based on what we already have
> >>>> in 'dummy_index_am'. 'dummy_table_am' provides a complete example of
> TAM
> >>>> reloptions definition.
> >>>>
> >>>> This work is directly derived from SadhuPrasad's patch here [2].
> Others
> >>>> attempts were posted here [1] and here [3].
> >>>>
> >>>> [1]
> https://www.postgresql.org/message-id/flat/429fb58fa3218221bb17c7bf9e70e1aa6cfc6b5d.camel%40j-davis.com
> >>>> [2]
> https://www.postgresql.org/message-id/flat/CAFF0-CG4KZHdtYHMsonWiXNzj16gWZpduXAn8yF7pDDub+GQMg(at)mail(dot)gmail(dot)com
> >>>> [3]
> https://www.postgresql.org/message-id/flat/AMUA1wBBBxfc3tKRLLdU64rb.1.1683276279979.Hmail.wuhao%40hashdata.cn
> >>> Please find a new version including minor fixes: 'TAM' terms are
> >>> replaced by 'table AM'
> >> Please find a new rebased version.
> > New rebased version.
> >
>
>
> This thread seems to have gone dormant, sadly. Here's a fresh attempt I
> made (with assistance from Claude), before I was aware of the existence
> of this and other efforts. I think it meets most of the previous
> objections, and is in line with what we do for Index AMs.
>
> I was testing this patch and found this issue,
CREATE EXTENSION dummy_table_am;
CREATE TABLE t (a int) USING dummy_table_am WITH (option_int = 42);
ALTER TABLE t SET ACCESS METHOD heap;
SELECT reloptions FROM pg_class WHERE oid = 't'::regclass;
reloptions
-----------------
{option_int=42}
(1 row)
ALTER TABLE t SET (fillfactor = 50);
2026-07-16 19:01:36.060 IST [95058] ERROR: unrecognized parameter
"option_int"
2026-07-16 19:01:36.060 IST [95058] STATEMENT: ALTER TABLE t SET
(fillfactor = 50);
ERROR: unrecognized parameter "option_int"

Basically, the option is left behind after changing the tableam to heap, I
think that isn't intentional.

>
> cheers
>
>
> andrew
>
>
> --
> Andrew Dunstan
> EDB: https://www.enterprisedb.com
>

--
Regards,
Rafia Sabih
CYBERTEC PostgreSQL International GmbH