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From: Michael Glaesemann <grzm@myrealbox.com>
To: David Pradier <dpradier@apartia.fr>
Cc: postgresql sql list <pgsql-sql@postgresql.org>
Subject: Re: UPDATEABLE VIEWS ... Examples?
Date: Mon, 20 Jun 2005 16:37:57 +0900
Message-ID: <3E0EA84A-7A3B-4BDC-ADB2-08D664551CD8@myrealbox.com> (raw)
In-Reply-To: <20050620071604.GB15942@apartia.fr>
References: <20050616180356.Y90456@ganymede.hub.org>
	<20050620071604.GB15942@apartia.fr>


On Jun 20, 2005, at 4:16 PM, David Pradier wrote:

> This is maybe a newbie question, but what is the difference with a
> materialized view ?

As I understand it (and that understanding may be wrong) a  
materialized view is a table that holds the values of a view from  
some point in time. A view is a "saved" subselect. Everything you  
call a view, the PostgreSQL backend re-evaluates the definition of  
the view. A materialized view is only as accurate as the last time it  
was updated. Things such as triggers can be used to keep the  
materialized view updated. The key issue with materialized views is  
to make sure it's always up-to-date with the evaluation of the view.

Michael Glaesemann
grzm myrealbox com





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