Re: trigger/rule question

From: Christoph Haller <ch(at)rodos(dot)fzk(dot)de>
To: weigelt(at)metux(dot)de
Cc: pgsql-sql <pgsql-sql(at)postgresql(dot)org>
Subject: Re: trigger/rule question
Date: 2005-05-02 07:58:04
Message-ID: 4275DD8C.EF29E7A1@rodos.fzk.de
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Enrico Weigelt wrote:
>
> * Christoph Haller <ch(at)rodos(dot)fzk(dot)de> wrote:
>
> Hi,
>
> > I assume this still refers to
> > [SQL] RULE for mtime recording
> > from last Friday.
>
> ehm, yeah. I forgot that I've already asked this stuff ...
> hmmpf. seems I'm not getting younger ;-)
>
> <snip>
> > I gave it another thought and
> > I am now having something which seems to work.
> > The trick is interpose a view to avoid the
> > rule recursion:
>
> <big_snip />
>
> correct me if I'm wrong:
>
> you dont let the application write to the actual storage table, but
> instead to a view, which a modified write to the actual storage, where
> also the reads get their data from.

Exactly.
>
> okay, that's really an idea worth to think about :)
>
> insert should work the same way. but how to implement delete ?
> (the application should only see one table, so in our case the view).

Exactly.
> if we user "DO INSTEAD", we wont get anything to delete (AFAIK), so
> we cannot intercept here. the only chance seems to leave out "INSTEAD"
> and live with duplicate data.

No. What's wrong with (referring to my previous post)

CREATE OR REPLACE RULE joo_delete
AS ON DELETE TO joo_view
DO INSTEAD
DELETE FROM joo
WHERE bar = OLD.bar ;

DELETE FROM joo_view WHERE bar = '...' ;

works perfectly for me

Or did I miss something here?
Regards, Christoph

>
> Did I miss anyting ?
>
> cu
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