Re: [BUG] Fix DETACH with FK pointing to a partitioned table fails

The foreign key still works even though partition was detached. Is this
behavior expected?
I can't find the answer in the document. If it is expected behavior ,
please ignore the bug I reported a few days ago.

tender wang <tndrwang@gmail.com> 于2023年8月4日周五 17:04写道：

> Oversight the DetachPartitionFinalize(), I found another bug below:
>
> postgres=# CREATE TABLE p ( id bigint PRIMARY KEY ) PARTITION BY list (id);
> CREATE TABLE
> postgres=# CREATE TABLE p_1 PARTITION OF p FOR VALUES IN (1);
> CREATE TABLE
> postgres=# CREATE TABLE r_1 (
> postgres(#     id   bigint PRIMARY KEY,
> postgres(#     p_id bigint NOT NULL
> postgres(#   );
> CREATE TABLE
> postgres=#  CREATE TABLE r (
> postgres(#     id   bigint PRIMARY KEY,
> postgres(#     p_id bigint NOT NULL,
> postgres(#     FOREIGN KEY (p_id) REFERENCES p (id)
> postgres(#   ) PARTITION BY list (id);
> CREATE TABLE
> postgres=# ALTER TABLE r ATTACH PARTITION r_1 FOR VALUES IN (1);
> ALTER TABLE
> postgres=# ALTER TABLE r DETACH PARTITION r_1;
> ALTER TABLE
> postgres=# insert into r_1 values(1,1);
> ERROR:  insert or update on table "r_1" violates foreign key constraint
> "r_p_id_fkey"
> DETAIL:  Key (p_id)=(1) is not present in table "p".
>
> After detach operation, r_1 is normal relation and the inherited foreign
> key 'r_p_id_fkey' should be removed.
>
>
> tender wang <tndrwang@gmail.com> 于2023年8月3日周四 17:34写道：
>
>> I think the code to determine that fk of a partition is inherited or not
>> is not enough.
>> For example, in this case, foreign key r_1_p_id_fkey1  is not inherited
>> from parent.
>>
>> If conform->conparentid(in DetachPartitionFinalize func) is valid, we
>> should recheck confrelid(pg_constraint) field.
>>
>> I try to fix this problem in the attached patch.
>> Any thoughts.
>>
>> Alvaro Herrera <alvherre@alvh.no-ip.org> 于2023年8月3日周四 17:02写道：
>>
>>> On 2023-Aug-03, tender wang wrote:
>>>
>>> > I think  old "sub-FK" should not be dropped, that will be violates
>>> foreign
>>> > key constraint.
>>>
>>> Yeah, I've been playing more with the patch and it is definitely not
>>> doing the right things.  Just eyeballing the contents of pg_trigger and
>>> pg_constraint for partitions added by ALTER...ATTACH shows that the
>>> catalog contents are inconsistent with those added by CREATE TABLE
>>> PARTITION OF.
>>>
>>> --
>>> Álvaro Herrera         PostgreSQL Developer  —
>>> https://www.EnterpriseDB.com/
>>>
>>