Re: conditional rule not applied

On Wed, 06 Jan 2010 09:39:45 -0600,
Seb <spluque(at)gmail(dot)com> wrote:

> Would this express the intention any better?

> CREATE RULE footwear_nothing_upd AS
> ON UPDATE TO footwear DO INSTEAD NOTHING;
> CREATE RULE footwear_newshoelaces_upd AS
> ON UPDATE TO footwear
> WHERE NOT EXISTS (SELECT sh_id FROM shoelaces WHERE NEW.sh_id=shoelaces.sh_id)
> DO
> INSERT INTO shoelaces (sh_id, sl_name)
> VALUES(NEW.sh_id, NEW.sl_name);

Adding to my confusion here, is the fact that the rule above seems to
work well, even though the docs say:

---<--------------------cut here---------------start------------------->---
condition

Any SQL conditional expression (returning boolean). The condition
expression cannot refer to any tables except NEW and OLD, and cannot
contain aggregate functions.
---<--------------------cut here---------------end--------------------->---

So the WHERE condition in the rule above should not be allowed since it
does reference a table other than NEW and OLD in the EXISTS statement.
Any enlightening comments appreciated.

--
Seb