nd_box_overlap()

static int nd_box_overlap ( const ND_STATS *  nd_stats, const ND_BOX *  nd_box, ND_IBOX *  nd_ibox  )

inlinestatic

What stats cells overlap with this ND_BOX? Put the lowest cell addresses in ND_IBOX->min and the highest in ND_IBOX->max.

Definition at line 670 of file gserialized_estimate.c.

{
        int d;
 
        POSTGIS_DEBUGF(4, " nd_box: %s", nd_box_to_json(nd_box, nd_stats->ndims));
 
        /* Initialize ibox */
        memset(nd_ibox, 0, sizeof(ND_IBOX));
 
        /* In each dimension... */
        for ( d = 0; d < nd_stats->ndims; d++ )
        {
                double smin = nd_stats->extent.min[d];
                double smax = nd_stats->extent.max[d];
                double width = smax - smin;
 
                if (width < MIN_DIMENSION_WIDTH)
                {
                        nd_ibox->min[d] = nd_ibox->max[d] = nd_stats->extent.min[d];
                }
                else
                {
                        int size = (int)roundf(nd_stats->size[d]);
 
                        /* ... find cells the box overlaps with in this dimension */
                        nd_ibox->min[d] = floor(size * (nd_box->min[d] - smin) / width);
                        nd_ibox->max[d] = floor(size * (nd_box->max[d] - smin) / width);
 
                        POSTGIS_DEBUGF(5, " stats: dim %d: min %g: max %g: width %g", d, smin, smax, width);
                        POSTGIS_DEBUGF(5, " overlap: dim %d: (%d, %d)", d, nd_ibox->min[d], nd_ibox->max[d]);
 
                        /* Push any out-of range values into range */
                        nd_ibox->min[d] = Max(nd_ibox->min[d], 0);
                        nd_ibox->max[d] = Min(nd_ibox->max[d], size - 1);
                }
        }
        return true;
}

References ND_STATS_T::extent, ND_BOX_T::max, ND_IBOX_T::max, ND_BOX_T::min, ND_IBOX_T::min, MIN_DIMENSION_WIDTH, nd_box_to_json(), ND_STATS_T::ndims, and ND_STATS_T::size.

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

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