Postgres Pro
Downloads
Home   >   mailing lists

Thread: SEQUENCE NAME syntax not documented for ALTER TABLE

SEQUENCE NAME syntax not documented for ALTER TABLE

From
Rene Saarsoo
Date:
The documentation for ALTER TABLE [1] doesn't make it clear that the following is allowed:
ALTER TABLE tbl
ALTER COLUMN id
ADD GENERATED BY DEFAULT AS IDENTITY (  SEQUENCE NAME my_name
);
It only references the sequence options allowed in CREATE SEQUENCE or ALTER SEQUENCE, unlike the CREATE TABLE [2] documentation, which does specifically state [3]:

> The available options include those shown for CREATE SEQUENCE,
> plus SEQUENCE NAME name, LOGGED, and UNLOGGED

With best,
Rene Saarsoo

Re: SEQUENCE NAME syntax not documented for ALTER TABLE

From
Tom Lane
Date:
Rene Saarsoo <nene@triin.net> writes:
> The documentation for ALTER TABLE [1] doesn't make it clear that the
> following is allowed:
> ...
> It only references the sequence options allowed in CREATE SEQUENCE or ALTER
> SEQUENCE, unlike the CREATE TABLE [2] documentation, which does
> specifically state [3]:

Huh?  I see

   <varlistentry id="sql-altertable-desc-generated-identity">
    <term><literal>ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY</literal></term>
    <term><literal>SET GENERATED { ALWAYS | BY DEFAULT }</literal></term>
    <term><literal>DROP IDENTITY [ IF EXISTS ]</literal></term>
    <listitem>
     <para>
      These forms change whether a column is an identity column or change the
      generation attribute of an existing identity column.
      See <link linkend="sql-createtable"><command>CREATE TABLE</command></link> for details.

Where do you see a pointer to CREATE SEQUENCE on that page?

            regards, tom lane

Re: SEQUENCE NAME syntax not documented for ALTER TABLE

From
Rene Saarsoo
Date:
On Sun, 23 Mar 2025 at 17:31, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Where do you see a pointer to CREATE SEQUENCE on that page?

Sorry, my mistake. The page only points to ALTER SEQUENCE.

Now I also see that separate section about ADD GENERATED etc,
which I completely missed earlier. I was searching for a definition of
sequence_options which is nowhere to be found on that page.
So I searched for the next best thing sequence_option (in singular)
and found the SET sequence_option section. I expected the definition
of sequence_options to just be the plural of sequence_option.
But confusingly it's not.

I personally would really prefer if this information was part of the main
syntax diagram, not somewhere deep inside the text. But I might be
an odd user of the documentation as I'm trying to write a parser for
PostgreSQL.

Regards,
Rene Saarsoo