"Jim Nasby" <decibel@decibel.org> writes:
> On Mar 21, 2007, at 5:11 AM, Tom Lane wrote:
>> constraint_exclusion
>>
>> I'm inclined not to worry about these, since changing them can't affect
>> the semantics of the query, at worst its performance.
>
> Hrm... wasn't that option added in case there was a bug in the exclusion code?
> I certainly can't think of any performance reason why you'd want to disable
> it... so it might be worth invalidating plans if it changes.
It was added precisely because we didn't have plan invalidation... If you
dropped a constraint there was previously nothing to force the plan to be
recalculated if it depended on the constraint for correctness.
-- Gregory Stark EnterpriseDB http://www.enterprisedb.com