Re: Fixing r-tree semantics

FYI, TODO has:

* Fix incorrect rtree results due to wrong assumptions about "over"
operator semantics [rtree]

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Tom Lane wrote:
> Hmmm ... just when you thought it was safe to go back in the water ...
>
> I was only looking closely at the "box" case earlier today, assuming
> that the polygon code was set up identically. Well, it isn't. In
> particular it appears that the poly_overleft and poly_overright
> definitions are different from box's, which means that rtrees are
> still broken for polygon searches.
>
> I'm of the opinion that this is a flat-out bug and we should just
> fix it, ie, change the operator definitions. The polygon definitions
> aren't even self-consistent (overleft accepts equality and overright
> doesn't).
>
> poly_left
> result = polya->boundbox.high.x < polyb->boundbox.low.x;
> poly_overleft:
> result = polya->boundbox.low.x <= polyb->boundbox.high.x;
> poly_right:
> result = polya->boundbox.low.x > polyb->boundbox.high.x;
> poly_overright:
> result = polya->boundbox.high.x > polyb->boundbox.low.x;
>
> By analogy to the box case these should be
>
> poly_overleft:
> result = polya->boundbox.high.x <= polyb->boundbox.high.x;
> poly_overright:
> result = polya->boundbox.low.x >= polyb->boundbox.low.x;
>
> regards, tom lane
>
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