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Re: DO INSTEAD and conditional rules

From: David Wheeler <david(at)kineticode(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>,Neil Conway <neilc(at)samurai(dot)com>, Jan Wieck <JanWieck(at)yahoo(dot)com>
Subject: Re: DO INSTEAD and conditional rules
Date: 2005-04-26 06:05:56
Message-ID: b2fef70cdda15b007cbb4fd1598dcd48@kineticode.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Apr 25, 2005, at 11:00 PM, Tom Lane wrote:

> DO INSTEAD means that the *original* query will not execute; it does
> not suppress actions produced by other rules.

Ah!

> If we did not define
> it that way, I think your example would have to error out --- how
> would you choose which INSTEAD rule wins?

The documentation says that they evaluate in alphabetical order by 
name. So I would expect that the first one to have its WHERE statement 
evaluate to true would short-circuit the execution of the remaining 
rules.

Regards,

David


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