Re: DOC: fixes multiple errors in alter table doc

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From: Chao Li <[email protected]>
To: Robert Treat <[email protected]>
Cc: Postgres hackers <[email protected]>
Subject: Re: DOC: fixes multiple errors in alter table doc
Date: Sun, 4 Jan 2026 12:30:36 +0800
Message-ID: <CAEoWx2kkh5kCZwYOYaOVShjh3un2mJTGrcFZyhJXd320PHYfJw@mail.gmail.com> (raw)
In-Reply-To: <CABV9wwMPmo-dg=oV+NaJGa_==uo5+TTvk58aNtjVQZBtMcRVBw@mail.gmail.com>
References: <CAEoWx2n6ShLMOnjOtf63TjjgGbgiTVT5OMsSOFmbjGb6Xue1Bw@mail.gmail.com>
	<CABV9wwMPmo-dg=oV+NaJGa_==uo5+TTvk58aNtjVQZBtMcRVBw@mail.gmail.com>

On Jan 2, 2026, at 10:54, Robert Treat <[email protected]> wrote:

Hi Robert,

Thanks you very much for your review.

On Thu, Dec 18, 2025 at 2:22 AM Chao Li <[email protected]> wrote:

Hi Hacker,

While working on a patch these days, my eyes are on the “alter table” doc,
and found multiple errors:

1. Several sub-commands are missed in the top “action” list:

  * ALTER COLUMN SET <sequence-option>
  * ALTER COLUMN RESTART

I believe these are covered by the line above them:

   ALTER [ COLUMN ] column_name { SET GENERATED { ALWAYS | BY DEFAULT
} | SET sequence_option | RESTART [ [ WITH ] restart ] } [...]

  * RENAME

This is covered by the 4th line

ALTER TABLE [ IF EXISTS ] name
   RENAME TO new_name

  * SET SCHEMA

5th option...

ALTER TABLE [ IF EXISTS ] name
   SET SCHEMA new_schema

  * ATTACH PARTITION
  * DETACH PARTITION
  * MERGE PARTITION
  * SPLIT PARTITION

And the above are the 7,8,9,10th options at the top.

That’s true. I reverted all above changes.

2. In sub-command details section, "ADD COLUMN [ IF NOT EXISTS ]” missed
“[]" with “COLUMN”, which is misleading, because “COLUMN” is actually
optional.

Seems technically correct and potentially useful, and I see you
handled this for the DROP COLUMN variant as well, so I could see a +1
on this one.

Thanks for confirming.

3. For all “alter column” sub-commands, "ALTER [ COLUMN ]” are omitted,
which is also confusing, because none of other sub-commands omit their
prefix part.

Hmm... I'm curious what you find confusing about this. Is the
confusion in trying to find or understand the information presented,
or confusing as to why it isn't all documented the same way? The
downside of your "fix" is that this introduces a lot of extra text
that is more or less noise, especially for folks trying to skim the
documents looking for very specific command references.  And while I
agree that we aren't 100% consistent on this within the ALTER TABLE
subcommands, we use this same mixed pattern of omission on other pages
(see ALTER TYPE for instance). If we were to insist on making this
consistent here, I think we'd probably need to look at other pages as
well and evaluate or update them too. I'm not sure that would be an
improvement though.

The confusion came from my own first-time reading of the documentation.
Since the page is quite long, when I was reading the action descriptions
and wanted to confirm the exact sub-command syntax, I often had to scroll
back up to the syntax section. That led me to think it might be helpful to
include the full sub-command form directly with the action descriptions.

That said, I understand your concern. The change did make the text longer
and added noise. In v2, I’ve therefore reverted that broader change. As you
pointed out, if we were to pursue this kind of consistency, it would need
to be handled across other similar pages as well, which would be better
done as a dedicated and more carefully scoped patch.

So, v2’s scope is significantly reduced, only a fix for my original point 2
is retained.

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

Attachments:

  [application/octet-stream] v2-0001-docs-reflect-optional-COLUMN-keyword-in-ALTER-TAB.patch (1.6K, ../CAEoWx2kkh5kCZwYOYaOVShjh3un2mJTGrcFZyhJXd320PHYfJw@mail.gmail.com/3-v2-0001-docs-reflect-optional-COLUMN-keyword-in-ALTER-TAB.patch)
  download | inline diff:
From 16b38fd753af4654ff6399938f6dcc11dbfb625d Mon Sep 17 00:00:00 2001
From: "Chao Li (Evan)" <[email protected]>
Date: Thu, 18 Dec 2025 15:18:22 +0800
Subject: [PATCH v2] docs: reflect optional COLUMN keyword in ALTER TABLE
 descriptions

The ALTER TABLE description entries for ADD COLUMN and DROP COLUMN
omitted the fact that the COLUMN keyword is optional. Adjust the
command summaries to match the documented syntax by marking COLUMN
as optional.

This is a documentation-only change; no behavior is altered.

Author: Chao Li <[email protected]>
---
 doc/src/sgml/ref/alter_table.sgml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 1bd479c917a..d69e5de8451 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -163,7 +163,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM

   <variablelist>
    <varlistentry id="sql-altertable-desc-add-column">
-    <term><literal>ADD COLUMN [ IF NOT EXISTS ]</literal></term>
+    <term><literal>ADD [ COLUMN ] [ IF NOT EXISTS ]</literal></term>
     <listitem>
      <para>
       This form adds a new column to the table, using the same syntax as
@@ -175,7 +175,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
    </varlistentry>

    <varlistentry id="sql-altertable-desc-drop-column">
-    <term><literal>DROP COLUMN [ IF EXISTS ]</literal></term>
+    <term><literal>DROP [ COLUMN ] [ IF EXISTS ]</literal></term>
     <listitem>
      <para>
       This form drops a column from a table.  Indexes and
-- 
2.39.5 (Apple Git-154)

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