Date: Mon, 19 Jan 2009 09:18:09 +0100
From: Bernd Helmle <mailings@oopsware.de>
To: Peter Eisentraut <peter_e@gmx.net>
cc: pgsql-hackers@postgresql.org
Subject: Re: WIP: Automatic view update rules
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--On Samstag, Januar 17, 2009 02:01:15 +0200 Peter Eisentraut 
<peter_e@gmx.net> wrote:

> * It is not clear how automatic rules and manual DO ALSO rules should
> interact.  A manual DO ALSO rule will currently clear out an automatic
> INSTEAD rule, which I find to be illogical.

My intentional feeling was that it would be a bad idea to leave any 
implicit rule when someone is going to create his own rule set on a view, 
at least to avoid any confusion or side effects. Consider someone having 
his own rules upgrading from an older version. He must have at least his 
own DO INSTEAD Rule, it doesn't make any sense to have his own DO ALSO Rule 
without an INSTEAD one. Thus, doing it this way will leave the view as 
expected from the original setup.

*thinking more*...if we teach explicit DO ALSO rules *not* to clean out 
implicit ones, we will have the following workflows:

a) View is updatable, has its own automatic DO INSTEAD rule: if someone is 
restoring his old update rules, he will have at least his own DO INSTEAD 
rule. This will drop any corresponding automatically created rule, adding 
his own DO INSTEAD rule and any DO ALSO rule.

b) View is updatable, has its own automatic DO INSTEAD rule: The user is 
able to create any additional DO ALSO rule.

I don't see any problems here, as long as the implicit DO INSTEAD rule gets 
replaced.

Opinions?

-- 
  Thanks

                    Bernd