Re: BUG #17618: unnecessary filter column <> text even after adding index

I wrote:
> I wonder if that isn't backwards, ie we should prefer to put duplicates
> in bitmapqualorig (the recheck condition) instead of qpqual (the filter).
> If my head is screwed on correctly today, that should allow us to skip
> checking the condition much of the time, and the skip would be safe
> if the index is correctly asserting that no recheck is needed.

Flipping the removal around has the effect I expected on the plan shape,
but some of the regression test queries now give the wrong answer, so
there's something faulty about that analysis.

            regards, tom lane