> Yeah, but I think we need to take that chance. At the very least, we
>> need to support the equivalent of a non-inherited CHECK (false) on
>> parent tables.
> Indeed. I usually enforce that with a trigger that raises an exception, but
> of course that doesn't help at all with constraint exclusion, and I saw a
> result just a few weeks ago (I forget the exact details) where it appeared
> that the plan chosen was significantly worse because the parent table wasn't
> excluded, so there's a non-trivial downside from having this restriction.
The downside appears to be non-trivial indeed! I cooked up the attached
patch to try to allow ALTER...ONLY...CHECK(false) on parent tables.
If this approach looks acceptable, I can provide a complete patch later with
some documentation changes (I think we ought to tell about this special case
in the documentation) and a minor test case along with it (if the need be
felt for the test case).
Although partitioning ought to be looked at from a different angle
completely, maybe this small patch can help out a bit in the current scheme
of things, although this is indeed a unusual special casing... Thoughts?
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