Date: Thu, 7 Jul 2005 16:44:52 -0600
From: Michael Fuhr <mike@fuhr.org>
To: PFC <lists@boutiquenumerique.com>
Cc: lmeadors@apache.org, pgsql-sql@postgresql.org
Subject: Re: getting back autonumber just inserted
Message-ID: <20050707224452.GA50696@winnie.fuhr.org>
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	<20050707201433.94901.qmail@web41013.mail.yahoo.com>
	<20050707203715.GA26528@winnie.fuhr.org>
	<a10a823c05070713473add03d7@mail.gmail.com>
	<20050707205725.GA28200@winnie.fuhr.org>
	<op.stkdygr8th1vuj@localhost>
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On Fri, Jul 08, 2005 at 12:26:30AM +0200, PFC wrote:
> 
> >That's a different issue than whether currval() is subject to
> >interference from other transactions.  And just wait until PostgreSQL
> >8.1 comes out and people start using lastval() -- then it could get
> >*really* confusing which sequence value you're getting.
> 
> What happens if an INSERT trigger inserts something into another 
> table  which also has a sequence ?

Do you mean with lastval()?  Here's what happens:

CREATE FUNCTION trigfunc() RETURNS trigger AS $$
BEGIN
    INSERT INTO bar (x) VALUES (NEW.x);
    RETURN NEW;
END;
$$ LANGUAGE plpgsql VOLATILE;

CREATE TABLE foo (id serial PRIMARY KEY, x integer);
CREATE TABLE bar (id serial PRIMARY KEY, x integer);

CREATE TRIGGER footrig BEFORE INSERT ON foo
  FOR EACH ROW EXECUTE PROCEDURE trigfunc();

ALTER SEQUENCE bar_id_seq RESTART WITH 50;

INSERT INTO foo (x) VALUES (12345);

SELECT lastval();
 lastval 
---------
      50
(1 row)

SELECT * FROM foo;
 id |   x   
----+-------
  1 | 12345
(1 row)

SELECT * FROM bar;
 id |   x   
----+-------
 50 | 12345
(1 row)

-- 
Michael Fuhr
http://www.fuhr.org/~mfuhr/