Re: BUG #18674: Partitioned table doesn't depend on access method it uses

On Mon, Oct 28, 2024 at 4:00 PM Alexander Lakhin <exclusion(at)gmail(dot)com> wrote:
>
> Hello Michael and Kirill,
>
> 28.10.2024 10:23, Michael Paquier wrote:
> > The path of adding the dependency between an AM and a table/matview is
> > heap_create_with_catalog() when these are defined. We can just expand
> > that for partitioned tables and simply fix the problem. Attached is a
> > patch to do that, with tests around create_am.sql based on USING
> > checking the contents of pg_depend.
>
> 0001-Fix-dependency....patch works for me, but while testing, I've also
> observed another questionable behavior:
> CREATE ACCESS METHOD heap2 TYPE TABLE HANDLER heap_tableam_handler;
> SET default_table_access_method = heap2;
> CREATE TABLE pt (a int) PARTITION BY LIST (a);
> \d+ pt
>
> doesn't show heap2 as access method for the table.
>
> Shouldn't default_table_access_method affect partitioned tables?

I think `default_table_access_method` should not affect partitioned tables,
the partition's access_method will be default_table_access_method as
wanted.

But if it affects partitioned tables, then the partitions will always
inherit the access method of the partitioned table.

You can try the following if you want it to affect partitioned tables:

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 1ccc80087c..434e82ab14 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -973,7 +973,7 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
accessMethodId =
get_rel_relam(linitial_oid(inheritOids));
}

- if (RELKIND_HAS_TABLE_AM(relkind) &&
!OidIsValid(accessMethodId))
+ if (!OidIsValid(accessMethodId))
accessMethodId =
get_table_am_oid(default_table_access_method, false);
}

>
> Best regards.
> Alexander
>
>

--
Regards
Junwang Zhao