On Wed, Nov 07, 2012 at 05:55:32PM -0500, Tom Lane wrote:
> David Fetter <david@fetter.org> writes:
> > On Wed, Nov 07, 2012 at 05:04:48PM -0500, Tom Lane wrote:
> >> Should we be doing something
> >> about such cases, or is playing dumb correct?
>
> > The SQL standard handles deciding the behavior based on whether WITH
> > CHECK OPTION is included in the view DDL. See the section 2 of the
> > SQL standard (Foundation) for details.
>
> Ah, I see it. So as long as we don't support WITH CHECK OPTION, we
> can ignore the issue.
I don't think it's as simple as all that. WITH CHECK OPTION is how
the SQL standard allows for creating update-able views in the first
place, so we want to be at least aware of what the standard mandates.
Here's what I'm able to apprehend from the standard.
There are three different WITH CHECK OPTION options:
WITH CHECK OPTION
WITH CASCADED CHECK OPTION
WITH LOCAL CHECK OPTION
- WITH CHECK OPTION means that the results of INSERTs and UPDATEs on the view must be consistent with the view
definition,i.e. INSERTs any of whose rows would be outside the view or UPDATEs which would push a row a row out of the
vieware disallowed.
- WITH CASCADED CHECK OPTION is like the above, but stricter in that they ensure by checking views which depend on the
viewwhere the write operation is happening. INSERTs and UPDATEs have to "stay in the lines" for those dependent
views.
- WITH LOCAL CHECK OPTION allows INSERTs or UPDATEs that violate the view definition so long as they comply with the
WITHCHECK OPTION on any dependent views. Apparently the LOCAL here means, "delegate any CHECK OPTION checking to the
dependentview, i.e. check it only locally and not right here."
Oh, and I'm guessing at least one well-known financial services
company would just love to have these :)
Cheers,
David.
--
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