Re: KNN-GiST with recheck

On Sun, Sep 14, 2014 at 10:09 PM, Emre Hasegeli <emre(at)hasegeli(dot)com> wrote:

> I added the point to polygon distance operator patch to the open
> CommitFest as ready for committer and added myself as reviewer to
> both of the patches.
>

Thanks.

> Cost estimation of GiST is a big problem anyway. It doesn't care (and
> > can't) about amount of recheck for regular operators. In this patch, same
> > would be for knn recheck. The problem is that touching heap from access
> > method breaks incapsulation. One idea about this is to do sorting in
> > another nodes. However, I wonder if it would be an overengineering and
> > overhead. In attached patch I propose a different approach: put code
> > touching heap into separate index_get_heap_values function. Also new
> > version of patch includes regression tests and some cleanup.
>
> While looking it at I found a bug. It returns the second column
> in wrong order when both of the distance functions return recheck = true.
> Test script attached to run on the regression database. I tried to
> fix but could not. searchTreeItemDistanceRecheck function is not
> very easy to follow. I think it deserves more comments.
>

Fixed, thanks. It was logical error in comparison function implementation.

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With best regards,
Alexander Korotkov.