*
**********************************************************************
* $Log$
+ * Revision 1.10 2004/02/25 00:46:26 strk
+ * initial version of && selectivity estimation for PG75
+ *
* Revision 1.9 2004/02/23 21:59:16 strk
* geometry analyzer builds the histogram
*
*/
#define STATISTIC_KIND_GEOMETRY 100
-#define DEBUG_GEOMETRY_STATS 0
+#define DEBUG_GEOMETRY_STATS 1
/*
* Default geometry selectivity factor
BOX *box = (BOX *) PG_GETARG_POINTER(1);
double box_area;
int x_idx_min, x_idx_max, y_idx_min, y_idx_max;
- double intersect_x, intersect_y,AOI;
+ double intersect_x, intersect_y, AOI;
int x,y;
double xmin,ymin,xmax,ymax;
int32 result_sum;
Oid operator = PG_GETARG_OID(1);
List *args = (List *) PG_GETARG_POINTER(2);
int varRelid = PG_GETARG_INT32(3);
+ Oid relid;
+ HeapTuple stats_tuple;
+ GEOM_STATS *geomstats;
+ int geomstats_nvalues=0;
+ Const *other;
+ Var *self;
+ GEOMETRY *in;
+ BOX *search_box;
+ float8 selectivity=0;
#if DEBUG_GEOMETRY_STATS
elog(NOTICE, "postgis_gist_sel called");
- elog(NOTICE, " returning default geometry selectivity");
#endif
- PG_RETURN_FLOAT8(DEFAULT_GEOMETRY_SEL);
+ /*
+ * Find the constant part
+ */
+
+ other = (Const *) lfirst(args);
+ if ( ! IsA(other, Const) )
+ {
+ self = (Var *)other;
+ other = (Const *) lsecond(args);
+ }
+ else
+ {
+ self = (Var *) lsecond(args);
+ }
+
+ if ( ! IsA(other, Const) )
+ {
+#if DEBUG_GEOMETRY_STATS
+ elog(NOTICE, " no constant arguments - returning default selectivity");
+#endif
+ PG_RETURN_FLOAT8(DEFAULT_GEOMETRY_SEL);
+ }
+
+ /*
+ * We are working on two constants..
+ * TODO: check if expression is true,
+ * returned set would be either
+ * the whole or none.
+ */
+ if ( ! IsA(self, Var) )
+ {
+#if DEBUG_GEOMETRY_STATS
+ elog(NOTICE, " no variable argument ? - returning default selectivity");
+#endif
+ PG_RETURN_FLOAT8(DEFAULT_GEOMETRY_SEL);
+ }
+
+ /*
+ * Convert the constant to a BOX
+ */
+
+ in = (GEOMETRY*)PG_DETOAST_DATUM( ((Const*)other)->constvalue );
+ search_box = convert_box3d_to_box(&in->bvol);
+#if DEBUG_GEOMETRY_STATS > 1
+ elog(NOTICE," requested search box is : %.15g %.15g, %.15g %.15g",search_box->low.x,search_box->low.y,search_box->high.x,search_box->high.y);
+#endif
+
+ /*
+ * Get pg_statistic row
+ */
+
+ relid = getrelid(varRelid, root->rtable);
+ stats_tuple = SearchSysCache(STATRELATT, ObjectIdGetDatum(relid), Int16GetDatum(self->varattno), 0, 0);
+ if ( ! stats_tuple )
+ {
+#if DEBUG_GEOMETRY_STATS
+ elog(NOTICE, " SearchSysCache returned NULL - ret.def.");
+#endif
+ ReleaseSysCache(stats_tuple);
+ PG_RETURN_FLOAT8(DEFAULT_GEOMETRY_SEL);
+ }
+
+
+ if ( ! get_attstatsslot(stats_tuple, 0, 0,
+ STATISTIC_KIND_GEOMETRY, InvalidOid, NULL, NULL,
+ (float4 **)&geomstats, &geomstats_nvalues) )
+ {
+#if DEBUG_GEOMETRY_STATS
+ elog(NOTICE, " STATISTIC_KIND_GEOMETRY stats not found - returning default geometry selectivity");
+#endif
+ ReleaseSysCache(stats_tuple);
+ PG_RETURN_FLOAT8(DEFAULT_GEOMETRY_SEL);
+
+ }
+
+#if DEBUG_GEOMETRY_STATS > 1
+ elog(NOTICE, " %d read from stats", geomstats_nvalues);
+#endif
+
+#if DEBUG_GEOMETRY_STATS > 1
+ 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
+
+ /*
+ * Do the estimation
+ */
+ {
+ int x, y;
+ int x_idx_min, x_idx_max, y_idx_min, y_idx_max;
+ double intersect_x, intersect_y, AOI;
+ double cell_area, box_area;
+ double geow, geoh; // width and height of histogram
+ int bps; // boxesPerSide
+ BOX *box;
+ double value;
+ int overlapping_cells;
+ double cell_value_weight;
+
+ box = search_box;
+ geow = geomstats->xmax-geomstats->xmin;
+ geoh = geomstats->ymax-geomstats->ymin;
+ bps = geomstats->boxesPerSide;
+ 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;
+ if (x_idx_min < 0) {
+ // should increment the value somehow
+ x_idx_min = 0;
+ }
+ if (x_idx_min >= bps)
+ {
+ // should increment the value somehow
+ x_idx_min = bps-1;
+ }
+
+ /* Find first overlapping row */
+ y_idx_min = (box->low.y-geomstats->ymin) / geoh * bps;
+ if (y_idx_min <0)
+ {
+ // should increment the value somehow
+ y_idx_min = 0;
+ }
+ if (y_idx_min >= bps)
+ {
+ // should increment the value somehow
+ y_idx_min = bps-1;
+ }
+
+ /* Find last overlapping column */
+ x_idx_max = (box->high.x-geomstats->xmin) / geow * bps;
+ if (x_idx_max <0)
+ {
+ // should increment the value somehow
+ x_idx_max = 0;
+ }
+ if (x_idx_max >= bps )
+ {
+ // should increment the value somehow
+ x_idx_max = bps-1;
+ }
+
+ /* Find last overlapping row */
+ y_idx_max = (box->high.y-geomstats->ymin) / geoh * bps;
+ if (y_idx_max <0)
+ {
+ // should increment the value somehow
+ y_idx_max = 0;
+ }
+ if (y_idx_max >= bps)
+ {
+ // should increment the value somehow
+ y_idx_max = bps-1;
+ }
+
+ /*
+ * the {x,y}_idx_{min,max}
+ * define the grid squares that the box intersects
+ */
+ for (y=y_idx_min; y<=y_idx_max; y++)
+ {
+ for (x=x_idx_min; x<=x_idx_max; x++)
+ {
+ double val;
+
+ 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) ;
+
+ val = geomstats->value[x+y*bps];
+
+ /*
+ * Of the cell value we get
+ * only the overlap fraction.
+ * I guess we can overlook this,
+ * we are not that precise anyway.
+ */
+ //AOI = intersect_x*intersect_y;
+ //val *= AOI/cell_area;
+
+ val *= cell_value_weight;
+#if DEBUG_GEOMETRY_STATS > 1
+ elog(NOTICE, " [%d,%d] adding %.15f to value",
+ x, y, val);
+#endif
+ value += 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.
+ *
+ * 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;
+ //selectivity = value/overlapping_cells;
+ //selectivity *= 0.1;
+ //selectivity = 0.9;
+ }
+
+#if DEBUG_GEOMETRY_STATS
+ elog(NOTICE, " returning computed value: %f", selectivity);
+#endif
+
+ free_attstatsslot(0, NULL, 0, (float *)geomstats, geomstats_nvalues);
+ ReleaseSysCache(stats_tuple);
+ PG_RETURN_FLOAT8(selectivity);
+
}
/*
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