nd_box_ratio()

static double nd_box_ratio ( const ND_BOX *  cover, const ND_BOX *  target, int  ndims  )

inlinestatic

Definition at line 201 of file gserialized_estimate_support.h.

{
        int d;
        bool fully_covered = true;
        double ivol = 1.0;
        double refvol = 1.0;
 
        for (d = 0; d < ndims; d++)
        {
                if (cover->max[d] <= target->min[d] || cover->min[d] >= target->max[d])
                        return 0.0; /* Disjoint */
 
                if (cover->min[d] > target->min[d] || cover->max[d] < target->max[d])
                        fully_covered = false;
        }
 
        if (fully_covered)
                return 1.0;
 
        for (d = 0; d < ndims; d++)
        {
                double width = target->max[d] - target->min[d];
                double imin = Max(cover->min[d], target->min[d]);
                double imax = Min(cover->max[d], target->max[d]);
                double iwidth = Max(0.0, imax - imin);
 
                refvol *= width;
                ivol *= iwidth;
        }
 
        if (refvol == 0.0)
                return refvol;
 
        return ivol / refvol;
}

References ND_BOX_T::max, and ND_BOX_T::min.

Referenced by compute_gserialized_stats_mode(), estimate_join_selectivity(), estimate_selectivity(), and nd_box_ratio_cases().

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