*
**********************************************************************
* $Log$
+ * Revision 1.11 2004/02/25 12:00:32 strk
+ * Added handling for point features in histogram creation (add 1 instead of AOI/cell_area when AOI is 0).
+ * Fixed a wrong cast of BOX3D to BOX (called the convertion func).
+ * Added some comments and an implementation on how to change evaluation
+ * based on the average feature and search box cells occupation.
+ *
* Revision 1.10 2004/02/25 00:46:26 strk
* initial version of && selectivity estimation for PG75
*
{
//boxesPerSide * boxesPerSide = total boxes in grid
float4 boxesPerSide;
- // average bbox area of features in this histogram
+
+ // average bounding box area of not-null features
float4 avgFeatureArea;
+
+ // average number of histogram cells
+ // covered by the sample not-null features
+ float4 avgFeatureCells;
+
// BOX of area
float4 xmin,ymin, xmax, ymax;
// variable length # of floats for histogram
geomstats->xmax, geomstats->ymax);
elog(NOTICE, " histo: boxesPerSide: %f", geomstats->boxesPerSide);
elog(NOTICE, " histo: avgFeatureArea: %f", geomstats->avgFeatureArea);
+ elog(NOTICE, " histo: avgFeatureCells: %d", geomstats->avgFeatureCells);
#endif
/*
int bps; // boxesPerSide
BOX *box;
double value;
- int overlapping_cells;
- double cell_value_weight;
+ float overlapping_cells;
+ float avg_feat_cells;
box = search_box;
geow = geomstats->xmax-geomstats->xmin;
cell_area = (geow*geoh) / (bps*bps);
box_area = (box->high.x-box->low.x)*(box->high.y-box->low.y);
value = 0;
- cell_value_weight = cell_area/geomstats->avgFeatureArea;
/* Find first overlapping column */
x_idx_min = (box->low.x-geomstats->xmin) / geow * bps;
//AOI = intersect_x*intersect_y;
//val *= AOI/cell_area;
- val *= cell_value_weight;
+ //val *= cell_value_weight;
#if DEBUG_GEOMETRY_STATS > 1
elog(NOTICE, " [%d,%d] adding %.15f to value",
x, y, val);
/*
- * If the box was a point, I suppose
- * the computed value would be good enough,
- * because it would express the fraction
- * of features overlapping a single histogram
- * cell.
+ * If the search_box is a point, it will
+ * overlap a single cell and thus get
+ * it's value, which is the fraction of
+ * samples (we can presume of row set also)
+ * which bumped to that cell.
+ *
+ * If the table features are points, each
+ * of them will overlap a single histogram cell.
+ * Our search_box value would then be correctly
+ * computed as the sum of the bumped cells values.
+ *
+ * If both our search_box AND the sample features
+ * overlap more then a single histogram cell we
+ * need to consider the fact that our sum computation
+ * will have many duplicated included. E.g. each
+ * single sample feature would have contributed to
+ * raise the search_box value by as many times as
+ * many cells in the histogram are commonly overlapped
+ * by both searc_box and feature. We should then
+ * divide our value by the number of cells in the virtual
+ * 'intersection' between average feature cell occupation
+ * and occupation of the search_box. This is as
+ * fuzzy as you understand it :)
+ *
+ * Consistency check: whenever the number of cells is
+ * one of whichever part (search_box_occupation,
+ * avg_feature_occupation) the 'intersection' must be 1.
+ * If sounds that our 'intersaction' is actually the
+ * minimun number between search_box_occupation and
+ * avg_feat_occupation.
*
- * TODO: should we consider the null fraction
- * or is it a job that the cost estimator
- * would do for us ?
*/
overlapping_cells = (x_idx_max-x_idx_min+1) *
(y_idx_max-x_idx_min+1);
- selectivity = value;
+ avg_feat_cells = geomstats->avgFeatureCells;
+#if DEBUG_GEOMETRY_STATS
+ elog(NOTICE, " search_box overlaps %f cells", overlapping_cells);
+ elog(NOTICE, " avg feat overlaps %f cells", avg_feat_cells);
+#endif
+ selectivity = (float8) value / (float8) min(overlapping_cells, avg_feat_cells);
//selectivity = value/overlapping_cells;
//selectivity *= 0.1;
//selectivity = 0.9;
{
MemoryContext old_context;
int i;
- int size;
+ int geom_stats_size;
BOX **sampleboxes;
GEOM_STATS *geomstats;
bool isnull;
BOX3D *sample_extent=NULL;
double total_width=0;
double total_boxes_area=0;
+ int total_boxes_cells=0;
double cell_area;
double geow, geoh; // width and height of histogram
int bps; // boxesPerSide
notnull_cnt++;
geom = (GEOMETRY *) PG_DETOAST_DATUM(datum);
- box = (BOX *)&(geom->bvol);
+ box = convert_box3d_to_box(&(geom->bvol));
sampleboxes[i] = box;
sample_extent = union_box3d(&(geom->bvol), sample_extent);
* Create the histogram (GEOM_STATS)
*/
old_context = MemoryContextSwitchTo(stats->anl_context);
- size=sizeof(GEOM_STATS)+
- (boxesPerSide*boxesPerSide-1)*sizeof(geomstats->value);
- geomstats = palloc(size);
+ geom_stats_size=sizeof(GEOM_STATS)+
+ (boxesPerSide*boxesPerSide-1)*sizeof(float4);
+ geomstats = palloc(geom_stats_size);
MemoryContextSwitchTo(old_context);
geomstats->xmin = sample_extent->LLB.x;
for (i=0;i<boxesPerSide*boxesPerSide; i++) geomstats->value[i] = 0;
-#if DEBUG_GEOMETRY_STATS
- elog(NOTICE, " histo: xmin,ymin: %f,%f",
- geomstats->xmin, geomstats->ymin);
- elog(NOTICE, " histo: xmax,ymax: %f,%f",
- geomstats->xmax, geomstats->ymax);
- elog(NOTICE, " histo: boxesPerSide: %f", geomstats->boxesPerSide);
- elog(NOTICE, " histo: avgFeatureArea: %f", geomstats->avgFeatureArea);
-#endif
-
geow = geomstats->xmax-geomstats->xmin;
geoh = geomstats->ymax-geomstats->ymin;
bps = geomstats->boxesPerSide;
* features' bbox overlaps: a feature's bvol
* can fully overlap (1) or partially overlap
* (fraction of 1) an histogram cell.
+ *
+ * o compute total cells occupation
*/
for (i=0; i<samplerows; i++)
{
int y_idx_min, y_idx_max, y;
double intersect_x, intersect_y;
double AOI; // area of intersection
+ int numcells=0;
if ( sampleboxes[i] == NULL ) continue;
box = (BOX *)sampleboxes[i];
+
+#if DEBUG_GEOMETRY_STATS > 2
+ elog(NOTICE, " feat %d box is %f %f, %f %f",
+ i, box->high.x, box->high.y,
+ box->low.x, box->low.y);
+#endif
/* Find first overlapping column */
x_idx_min = (box->low.x-geomstats->xmin) / geow * bps;
y_idx_max = (box->high.y-geomstats->ymin) / geoh * bps;
if (y_idx_max <0) y_idx_max = 0;
if (y_idx_max >= bps) y_idx_max = bps-1;
+#if DEBUG_GEOMETRY_STATS > 2
+ elog(NOTICE, " feat %d overlaps columns %d-%d, rows %d-%d",
+ i, x_idx_min, x_idx_max, y_idx_min, y_idx_max);
+#endif
/*
* the {x,y}_idx_{min,max}
intersect_y = min(box->high.y, geomstats->ymin + (y+1) * geoh / bps) -
max(box->low.y, geomstats->ymin+ y * geoh / bps) ;
AOI = intersect_x*intersect_y;
- geomstats->value[x+y*bps] += AOI / cell_area;
+ if ( ! AOI ) // must be a point
+ {
+ geomstats->value[x+y*bps] += 1;
+ }
+ else
+ {
+ geomstats->value[x+y*bps] += AOI / cell_area;
+ }
+ numcells++;
}
}
+
+ // before adding to the total cells
+ // we could decide if we really
+ // want this feature to count
+ total_boxes_cells += numcells;
}
+ // what about null features (TODO) ?
+ geomstats->avgFeatureCells = (float4)total_boxes_cells/notnull_cnt;
+
+#if DEBUG_GEOMETRY_STATS
+ elog(NOTICE, " histo: total_boxes_cells: %d", total_boxes_cells);
+ elog(NOTICE, " histo: xmin,ymin: %f,%f",
+ geomstats->xmin, geomstats->ymin);
+ elog(NOTICE, " histo: xmax,ymax: %f,%f",
+ geomstats->xmax, geomstats->ymax);
+ elog(NOTICE, " histo: boxesPerSide: %f", geomstats->boxesPerSide);
+ elog(NOTICE, " histo: avgFeatureArea: %f", geomstats->avgFeatureArea);
+ elog(NOTICE, " histo: avgFeatureCells: %f", geomstats->avgFeatureCells);
+#endif
+
+
/*
* Normalize histogram
+ *
+ * We divide each histogram cell value
+ * by the number of samples examined.
+ *
*/
for (i=0;i<boxesPerSide*boxesPerSide; i++)
geomstats->value[i] /= samplerows;
-#if DEBUG_GEOMETRY_STATS > 1
+#if 0 & DEBUG_GEOMETRY_STATS > 1
{
int x, y;
for (x=0; x<bps; x++)
stats->stakind[0] = STATISTIC_KIND_GEOMETRY;
stats->staop[0] = InvalidOid;
stats->stanumbers[0] = (float4 *)geomstats;
- stats->numnumbers[0] = boxesPerSide*boxesPerSide+6;
+ stats->numnumbers[0] = geom_stats_size/sizeof(float4);
stats->stanullfrac = null_cnt/samplerows;
stats->stawidth = total_width/notnull_cnt;
#if DEBUG_GEOMETRY_STATS
elog(NOTICE, " out: slot 0: kind %d (STATISTIC_KIND_GEOMETRY)",
- stats->stakind[0]);
+ stats->stakind[0]);
elog(NOTICE, " out: slot 0: op %d (InvalidOid)", stats->staop[0]);
elog(NOTICE, " out: slot 0: numnumbers %d", stats->numnumbers[0]);
elog(NOTICE, " out: null fraction: %d/%d", null_cnt, samplerows);
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