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From: Josh Berkus <josh@agliodbs.com>
Reply-To: josh@agliodbs.com
Organization: Aglio Database Solutions
To: Bruce Momjian <pgman@candle.pha.pa.us>
Subject: Re: Rules/Trigges Trade-offs
Date: Fri, 6 Dec 2002 15:54:07 -0800
Cc: Jean-Luc Lachance <jllachan@nsd.ca>, pgsql-sql <pgsql-sql@postgresql.org>
References: <200212062330.gB6NUDl20018@candle.pha.pa.us>
In-Reply-To: <200212062330.gB6NUDl20018@candle.pha.pa.us>
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Message-Id: <200212061554.07415.josh@agliodbs.com>


Bruce,

> > 1) Rules can't use indexes to do their processing, so Rules which query=
=20
large=20
> > secondary tables can be a bad idea (maybe this has changed?)
>=20
> I don't think this is true.  Rewrite is before optimizer so it should be
> optimized just the same.

I was speaking if the Rule has to do a lookup on a 2nd table in the course =
of=20
its processing; it used to be that such a lookup could not use indexes=20
because Rules are pre-optimizer.   This could have changed since 7.1, thoug=
h.

> > 3) There are no AFTER Rules, making, for example, a rule with a table=
=20
check on=20
> > the new data impractical, so you'd want to use Triggers or Constraints
>=20
> We have changed ordering in 7.3 where I think INSERT rules are _after_
> the insert.

How would that work?  What if I want to reject the insert?


--=20
-Josh Berkus
 Aglio Database Solutions
 San Francisco