Re: [PATCHES] Updatable views

Bernd Helmle wrote:

> <tgl@sss.pgh.pa.us> wrote:

> >* It's too early in the morning for me to be clear about the difference
> >between CASCADED and LOCAL CHECK OPTION --- I think that this would
> >merely alter the set of check constraints collected for a particular
> >query, but if there's something more fundamental there, this scheme
> >might not work at all.  So look into that first.
> 
> LOCAL checks the data to be updated against its own view WHERE
> condition only, where CASCADED involves all WHERE conditions of all
> underlying views.

I don't understand this part very well.  Say if you have a view WITH
CHECK OPTION whose condition is "foo > 5", and then define a view WITH
LOCAL CHECK OPTION on top of that, whose condition is "bar > 5".  Does
the local check option on the second view that I can insert a row with
foo=4, bar=6?  That doesn't violate the condition of bar > 5, so it
seems fine to me.  But it also seems quite idiotic because it violated
the original foo>5 condition.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.