Oh the use of default keyword is new to me, thanks for that.

But to make PostgreSQL more Informix-compatible, zero should have been 
considered as well.

Informix:

sf@toro:/tmp$ dbaccess test1 -
Database selected.
> create table mytable ( pkey serial not null primary key, name varchar(50) );
Table created.

> insert into mytable values ( 0, 'aaaaa' );
1 row(s) inserted.

> select * from mytable;
       pkey name
          1 aaaaa
1 row(s) retrieved.


PostgreSQL:

sf@toro:/tmp$ psql test1 --host=localhost --port=5436 --user=pgsuser
psql (14.1)
Type "help" for help.

test1=> create table mytable ( pkey serial not null primary key, name 
varchar(50) );
CREATE TABLE

test1=> insert into mytable values ( 0, 'aaaaa' );
INSERT 0 1

test1=> select * from mytable;
 pkey | name
------+-------
    0 | aaaaa
(1 row)



So, I would rather say : no, using zero was not considered.

😉
Seb

________________________________
From: Adrian Klaver <adrian.kla...@aklaver.com>
Sent: Wednesday, March 29, 2023 4:59 PM
To: Sebastien Flaesch <sebastien.flae...@4js.com>; Kirk Wolak <wol...@gmail.com>
Cc: Geoff Winkless <pgsqlad...@geoff.dj>; pgsql-general 
<pgsql-general@lists.postgresql.org>
Subject: Re: Using CTID system column as a "temporary" primary key

EXTERNAL: Do not click links or open attachments if you do not recognize the 
sender.

On 3/29/23 07:19, Sebastien Flaesch wrote:
> Hello Kirk,
>

> INSERT statements must not use the serial column, so you have to list
> all columns of the table and provide only the values of the non-serial
> columns. With Informix you could just specific a zero to get a new
> generated serial, but seems this has never been considered with PostgreSQL.

Yes it has:

  \d seq_test
                                  Table "public.seq_test"
  Column |       Type        | Collation | Nullable |
Default
--------+-------------------+-----------+----------+--------------------------------------
  id     | integer           |           | not null |
nextval('seq_test_id_seq'::regclass)
  fld_1  | character varying |           |          |
Indexes:
     "seq_test_pkey" PRIMARY KEY, btree (id)

insert into seq_test values(default, 'test');

select * from seq_test;
  id | fld_1
----+-------
   1 | test


>
> SELECT * FROM table will return all column, user-defined ROWID included...
> This is not the case with Informix or Oracle ROWID columns.
> So, either you specify all columns except user-def ROWID or you add the
> rowid field to the program variable structure that receives the row.
>
> ...
>
> Seb
> ------------------------------------------------------------------------

--
Adrian Klaver
adrian.kla...@aklaver.com

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