Re: CHECK NO INHERIT syntax

On Thu, Jul 19, 2012 at 12:49:37AM +0300, Peter Eisentraut wrote:
> Sorry to raise this once again, but I still find this CHECK NO INHERIT
> syntax to a bit funny. We are currently using something like
>
> CHECK NO INHERIT (foo > 0)
>
> But we already have a different syntax for attaching attributes to
> constraints (NOT DEFERRABLE, NOT VALID, etc.), so it would make more
> sense to have
>
> CHECK (foo > 0) NO INHERIT

How about this?

CHECK (foo > 0) (INHERIT FALSE)

That leaves an obvious place for other options, which will doubtless
come. EXPLAIN's options inspired this API design.

> Besides consistency, this makes more sense, because the attribute is a
> property of the constraint as a whole, not of the "checking".

Good point. The above change preserves this property.

> This would also extend more easily to other constraint types. For
> example, when unifying CHECK and NOT NULL constraints, as is
> planned, or when allowing inherited unique constraints, as is
> planned further down the road.
>
> There is also a hole in the current implementation. Domain
> constraints silently allow NO INHERIT to be specified, even though
> other senseless attributes are rejected.

That's probably a bug.

Cheers,
David.
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