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From: Alexander Korotkov <aekorotkov@gmail.com>
Date: Sat, 20 Dec 2025 13:07:51 +0200
Message-ID: 
 <CAPpHfdvs-U0HQWnhe8e7B=K5k=c9FvvA39UcqnmNoLqbkgAfjw@mail.gmail.com>
Subject: Re: Add SPLIT PARTITION/MERGE PARTITIONS commands
To: Tender Wang <tndrwang@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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Hi Tender,

On Sat, Dec 20, 2025 at 5:18=E2=80=AFAM Tender Wang <tndrwang@gmail.com> wr=
ote:
> I found this feature merged; thanks for this work.
> I tested it and found that one place in the error errcode may need to be =
changed.
> In checkPartition():
> ...
> if (get_partition_parent(partRelOid, false) !=3D RelationGetRelid(rel))
>     ereport(ERROR,
>     errcode(ERRCODE_UNDEFINED_TABLE),
>     errmsg("relation \"%s\" is not a partition of relation \"%s\"",
> ...
>
> ERRCODE_UNDEFINED_TABLE usually means "table does not exist."
> When entering here, the table should exist, otherwise table_open() alread=
y reports an error.
> I found another two errcode in checkPartition() use ERRCODE_WRONG_OBJECT_=
TYPE,
> In the attached patch, I replace ERRCODE_UNDEFINED_TABLE with ERRCODE_WRO=
NG_OBJECT_TYPE.

I agree with you that ERRCODE_UNDEFINED_TABLE is certainly wrong error
code because the table actually exists.  ERRCODE_WRONG_OBJECT_TYPE is
better.  For example, we throw it when trying to attach a partition to
non-partitioned table.  So, the parent table type is wrong.  However,
are objects in the situation under consideration really have wrong
type?  The problem is that one table is not partition of another.
However, it's possibly that they could be attached without changing of
their types.  So, I think about
ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE.  What do you think?

------
Regards,
Alexander Korotkov
Supabase