Date: Thu, 23 Jul 2009 06:55:16 -0400
From: Stephen Frost <sfrost@snowman.net>
To: Glenn Maynard <glenn@zewt.org>
Cc: Richard Huxton <dev@archonet.com>, pgsql-sql@postgresql.org
Subject: Re: Bit by "commands ignored until end of transaction block"
	again
Message-ID: <20090723105516.GJ23840@tamriel.snowman.net>
References: <bd36f99e0907222158k6b4b3a0al65766c0d9c4906cf@mail.gmail.com>
	<4A67F5B6.4080409@archonet.com>
	<bd36f99e0907222304x38cfa50bkeba19f7c9b2694@mail.gmail.com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha1;
	protocol="application/pgp-signature"; boundary="jIYo0VRlfdMI9fLa"
Content-Disposition: inline
In-Reply-To: <bd36f99e0907222304x38cfa50bkeba19f7c9b2694@mail.gmail.com>
User-Agent: Mutt/1.5.18 (2008-05-17)


--jIYo0VRlfdMI9fLa
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

* Glenn Maynard (glenn@zewt.org) wrote:
> > The ORM can't control transactions, can't call functions or can't set
> > savepoints?
>=20
> It can't write the necessary SQL to say "insert this unless it already
> exists", namely:

If it can't cleanly handle failure cases like this one, then I think
your issue is with your ORM and not with PG.  An INSERT failing on a
uniqueness violation is actually a rather big deal in a relational
database and not erroring on it goes quite against data integrity
considerations.

If your ORM could call a function instead, you could handle the insert
and error-check in the function, to make up for the lack of intelligence
in the ORM.  Another option would be to have a 'fake' table, which has
no rows in it and just has an 'ON INSERT' trigger that calls a function
to handle this.  That could also be a view with a do-instead rule, if
the ORM has to query the same table.

I would think the time would better be spent fixing the ORM though.

	Thanks,

		Stephen

--jIYo0VRlfdMI9fLa
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: Digital signature
Content-Disposition: inline

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.9 (GNU/Linux)

iEYEARECAAYFAkpoQZQACgkQrzgMPqB3kigL7wCeNRI5ot+xp5hxnQlZNtUVn1mn
+gMAoIgfTp45dtfNo1UthwvDgvzC2UAu
=pkgx
-----END PGP SIGNATURE-----

--jIYo0VRlfdMI9fLa--