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Subject: Re: docs: clarify ALTER TABLE behavior on partitioned tables
From: Chao Li <li.evan.chao@gmail.com>
In-Reply-To: <1852615.1774810890@sss.pgh.pa.us>
Date: Mon, 30 Mar 2026 11:06:18 +0800
Cc: "David G. Johnston" <david.g.johnston@gmail.com>,
 Zsolt Parragi <zsolt.parragi@percona.com>,
 Postgres hackers <pgsql-hackers@lists.postgresql.org>,
 Amit Kapila <amit.kapila16@gmail.com>
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To: Tom Lane <tgl@sss.pgh.pa.us>
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> On Mar 30, 2026, at 03:01, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>=20
> Chao Li <li.evan.chao@gmail.com> writes:
>> PFA v10 - just integrated v9-0002-diff into the patch.
>=20
> I do not like this patch *at all*.  It removes the documentation
> that enunciates the general principles ALTER is following, such as
>=20
> -    If a table has any descendant tables, it is not permitted to add,
> -    rename, or change the type of a column in the parent table =
without doing
> -    the same to the descendants.  This ensures that the descendants =
always
> -    have columns matching the parent.  Similarly, a =
<literal>CHECK</literal>
>=20
> and replaces that with highly repetitive, explanation-free
> statements like "Specifying <literal>ONLY</literal> is not allowed"
> for each option.  I don't see how this set of changes is an =
improvement.
> It's also close to unreviewable, since it's so hard to see whether
> those statements have been attached to all and only the proper
> options.
>=20
> If there's mistakes in the existing text, by all means let's fix
> them.  But this doesn't seem like the way to go about it.
>=20
> By the by, I believe that our general project style is to leave a
> blank line between <para> units.  So I also don't approve of the
> patch making a concerted effort to remove a lot of those blank
> lines, especially when it's doing that to just one file.
>=20
> regards, tom lane

Hi Tom,

Thanks for your comments.

The main goal of this patch is to clarify how ALTER TABLE sub-commands =
behave on partitioned tables, since the current behavior is not always =
consistent or easy to predict. Because of that, some per-subcommand =
verification is probably unavoidable. But I agree the current patch may =
make that harder than it should be.

I also was not aware of the blank-line style convention. In any case, =
that part is easy to fix.

I=E2=80=99ll rework the patch to better address your concerns.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/