Re: pg_dumpall and check constraints

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От Stephan Szabo
Тема Re: pg_dumpall and check constraints
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Msg-id 001501bfe301$c5e847f0$0c64010a@kick.com
обсуждение исходный текст
Ответ на Re: pg_dumpall and check constraints  (Guillaume Perréal <perreal@lyon.cemagref.fr>)
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> >    How should a RESTRICT  or  ON
> >    DELETE CASCADE work in that scenario?
>
> Perhaps as Check constraints on all tables in the view...for the most part
> I would not expect complex views to be used in this way, but since this is
> what the user would have to do anyway, why not do it for them?

I'd say that for right now, way to complicated...  Any non-trivial view
would be an incredible pain.  Although, once we properly insist on there
being a unique constraint on the columns referenced, it would probably
be easier (although can you actually put a unique constraint on a view?)

Take, for example,
create view x as select a.id, c.name from a,b,c where a.id=b.id and
a.type=c.type
and b.customerid=c.id and c.name < 'Smith';
So, what it the deletion constraint on table c?  It's something like, you
can't delete
a row in c that has a name < 'Smith' and who matches up with an a,b row
based on
the other constraints and has a referencing row in the table you made the
reference
from, but I'm not even 100% sure of that.  And heaven help you if there are
subqueries.

And of course, the cascade, set null and set default are even stranger.



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