The selectivity estimator does add the full value of each cell it overlaps,

regardless of the actual overlapping area. Final gain is not applied
(formerly 1 / minimun between average feature cells occupation and
 search_box cells occupation)

git-svn-id: http://svn.osgeo.org/postgis/trunk@461 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/postgis_estimate.c b/postgis_estimate.c
index d2ba189dab52c1086d444e7601c44c559ccaaf7e..9ba11bb9253298525a33d8725c28de3666986211 100644 (file)
--- a/postgis_estimate.c
+++ b/postgis_estimate.c
@@ -11,6 +11,12 @@
  * 
  **********************************************************************
  * $Log$
+ * Revision 1.16  2004/03/04 09:44:57  strk
+ * The selectivity estimator does add the full value of each cell it overlaps,
+ * regardless of the actual overlapping area. Final gain is not applied
+ * (formerly 1 / minimun between average feature cells occupation and
+ *  search_box cells occupation)
+ *
  * Revision 1.15  2004/03/03 21:59:48  strk
  * added check to keep selectivity value in the range of validity (suggested by m.cave)
  *
@@ -1073,6 +1079,7 @@ Datum postgis_gist_sel(PG_FUNCTION_ARGS)
                double value;
                float overlapping_cells;
                float avg_feat_cells;
+               double gain;
 
                box = search_box;
                geow = geomstats->xmax-geomstats->xmin;
@@ -1142,6 +1149,7 @@ Datum postgis_gist_sel(PG_FUNCTION_ARGS)
                        for (x=x_idx_min; x<=x_idx_max; x++)
                        {
                                double val;
+                               double gain;
 
                                val = geomstats->value[x+y*bps];
 
@@ -1155,7 +1163,17 @@ Datum postgis_gist_sel(PG_FUNCTION_ARGS)
                                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;
-                               val *= AOI/cell_area;
+                               //gain = AOI/cell_area;
+                               gain = 1;
+
+#if DEBUG_GEOMETRY_STATS > 1
+                               elog(NOTICE, " [%d,%d] cell val %.15f",
+                                               x, y, val);
+                               elog(NOTICE, " [%d,%d] gain %.15f",
+                                               x, y, gain);
+#endif
+
+                               val *= gain;
 
 #if DEBUG_GEOMETRY_STATS > 1
                                elog(NOTICE, " [%d,%d] adding %.15f to value",
@@ -1206,7 +1224,18 @@ Datum postgis_gist_sel(PG_FUNCTION_ARGS)
        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);
+
+               gain = 1;
+
+
+               //selectivity = (float8) value / (float8) min(overlapping_cells, avg_feat_cells);
+               selectivity = value*gain;
+
+#if DEBUG_GEOMETRY_STATS
+               elog(NOTICE, " SUM(ov_histo_cells)=%f", value);
+               elog(NOTICE, " gain=%f", gain);
+               elog(NOTICE, " selectivity=%f", selectivity);
+#endif
 
                /* prevent rounding overflows */
                if (selectivity > 1.0) selectivity = 1.0;
@@ -1258,6 +1287,8 @@ compute_geometry_stats(VacAttrStats *stats, AnalyzeAttrFetchFunc fetchfunc,
        double total_boxes_area=0;
        int total_boxes_cells=0;
        double cell_area;
+       double cell_width;
+       double cell_height;
        double geow, geoh; // width and height of histogram
        int bps; // boxesPerSide  (alias)
        int boxesPerSide;
@@ -1344,7 +1375,14 @@ compute_geometry_stats(VacAttrStats *stats, AnalyzeAttrFetchFunc fetchfunc,
        geow = geomstats->xmax-geomstats->xmin;
        geoh = geomstats->ymax-geomstats->ymin;
        bps = geomstats->boxesPerSide;
-       cell_area = (geow*geoh) / (bps*bps);
+       cell_width = geow/bps;
+       cell_height = geoh/bps;
+       cell_area = cell_width*cell_height;
+
+#if DEBUG_GEOMETRY_STATS > 2
+       elog(NOTICE, "cell_width: %f", cell_width);
+       elog(NOTICE, "cell_height: %f", cell_height);
+#endif
        
 
        /*
@@ -1404,13 +1442,29 @@ compute_geometry_stats(VacAttrStats *stats, AnalyzeAttrFetchFunc fetchfunc,
                 */
                for (y=y_idx_min; y<=y_idx_max; y++)
                {
+                       double cell_xmax = geomstats->xmin+(x+1)*cell_width;
+                       double cell_xmin = geomstats->xmin+x*cell_width;
+                       double cell_ymax = geomstats->ymin+(y+1)*cell_height;
+                       double cell_ymin = geomstats->ymin+y*cell_height;
+
                        for (x=x_idx_min; x<=x_idx_max; x++)
                        {
-                               intersect_x = min(box->high.x, geomstats->xmin + (x+1) * geow / bps) -
-                                       max(box->low.x, geomstats->xmin + x * geow / bps );
-                               intersect_y = min(box->high.y, geomstats->ymin + (y+1) * geoh / bps) -
-                                       max(box->low.y, geomstats->ymin+ y * geoh / bps) ;
+                               cell_xmax = geomstats->xmin+(x+1)*cell_width;
+                               cell_xmin = geomstats->xmin+x*cell_width;
+
+                               intersect_x = min(box->high.x, cell_xmax) -
+                                       max(box->low.x, cell_xmin);
+                               intersect_y = min(box->high.y, cell_ymax) -
+                                       max(box->low.y, cell_ymin);
+
+#if DEBUG_GEOMETRY_STATS > 2
+elog(NOTICE, "r=%d c=%d intx=%f inty=%f",
+               y, x, intersect_x, intersect_y);
+#endif
+
                                AOI = intersect_x*intersect_y;
+
+
                                if ( ! AOI ) // must be a point
                                {
                        geomstats->value[x+y*bps] += 1;