From: Tom Lane <tgl@sss.pgh.pa.us>
To: mohen.lhy@alibaba-inc.com
cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #19100: Different column type between partitioned table and
 detached pending partition table make errors
In-reply-to: <19100-f676a0f5c4723b2f@postgresql.org>
References: <19100-f676a0f5c4723b2f@postgresql.org>
Comments: In-reply-to PG Bug reporting form <noreply@postgresql.org>
	message dated "Sat, 01 Nov 2025 18:36:26 -0000"
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Date: Sun, 02 Nov 2025 13:36:12 -0500
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PG Bug reporting form <noreply@postgresql.org> writes:
> It's evident that in both error cases, the failure occurs because
> column name has different data types between the parent and the child
> table. BTW, "\d+ users_p0" error happens when
> pg_get_partition_constraintdef() is called. The root cause seems to be
> that when running:
> ```
> ALTER TABLE users ALTER COLUMN name TYPE char(10);
> ```
> on the parent table, the statement does not affect a child table that is in
> detach pending state.

Ugh.

> IMO, a detach pending child table is not affected by parent's DML or DQL,
> but should still be affected by parent's DDL.

I think it'd be far safer to refuse all forms of ALTER TABLE until the
detach is completed.

			regards, tom lane