Fix a bug with building rtree_gist indexes.

Patch from Teodor Sigaev.

contrib/rtree_gist/rtree_gist.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	$Header: /cvsroot/pgsql/contrib/rtree_gist/Attic/rtree_gist.c,v 1.4 2001/10/25 05:49:20 momjian Exp $
+ *	$Header: /cvsroot/pgsql/contrib/rtree_gist/Attic/rtree_gist.c,v 1.5 2002/05/28 15:24:53 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -161,6 +161,22 @@ gbox_penalty(PG_FUNCTION_ARGS)
 	PG_RETURN_POINTER(result);
 }
 
+typedef struct {
+	BOX 	*key;
+	int 	pos;
+} KBsort;
+
+static int
+compare_KB(const void* a, const void* b) {
+	BOX *abox = ((KBsort*)a)->key; 
+	BOX *bbox = ((KBsort*)b)->key;
+	float sa = (abox->high.x - abox->low.x) * (abox->high.y - abox->low.y);
+	float sb = (bbox->high.x - bbox->low.x) * (bbox->high.y - bbox->low.y);
+
+	if ( sa==sb ) return 0;
+	return ( sa>sb ) ? 1 : -1;
+}
+
 /*
 ** The GiST PickSplit method
 ** New linear algorithm, see 'New Linear Node Splitting Algorithm for R-tree',
@@ -201,26 +217,22 @@ gbox_picksplit(PG_FUNCTION_ARGS)
 	for (i = OffsetNumberNext(FirstOffsetNumber); i <= maxoff; i = OffsetNumberNext(i))
 	{
 		cur = DatumGetBoxP(((GISTENTRY *) VARDATA(entryvec))[i].key);
-		if (pageunion.high.x < cur->high.x)
-		{
+		if ( allisequal == true &&  (
+				pageunion.high.x != cur->high.x || 
+				pageunion.high.y != cur->high.y || 
+				pageunion.low.x != cur->low.x || 
+				pageunion.low.y != cur->low.y 
+			) ) 
 			allisequal = false;
+ 
+		if (pageunion.high.x < cur->high.x)
 			pageunion.high.x = cur->high.x;
-		}
 		if (pageunion.low.x > cur->low.x)
-		{
-			allisequal = false;
 			pageunion.low.x = cur->low.x;
-		}
 		if (pageunion.high.y < cur->high.y)
-		{
-			allisequal = false;
 			pageunion.high.y = cur->high.y;
-		}
 		if (pageunion.low.y > cur->low.y)
-		{
-			allisequal = false;
 			pageunion.low.y = cur->low.y;
-		}
 	}
 
 	nbytes = (maxoff + 2) * sizeof(OffsetNumber);
@@ -264,7 +276,7 @@ gbox_picksplit(PG_FUNCTION_ARGS)
 	unionB = (BOX *) palloc(sizeof(BOX));
 	unionT = (BOX *) palloc(sizeof(BOX));
 
-#define ADDLIST( list, unionD, pos ) do { \
+#define ADDLIST( list, unionD, pos, num ) do { \
 	if ( pos ) { \
 		if ( unionD->high.x < cur->high.x ) unionD->high.x	= cur->high.x; \
 		if ( unionD->low.x	> cur->low.x  ) unionD->low.x	= cur->low.x; \
@@ -273,7 +285,7 @@ gbox_picksplit(PG_FUNCTION_ARGS)
 	} else { \
 			memcpy( (void*)unionD, (void*) cur, sizeof( BOX ) );  \
 	} \
-	list[pos] = i; \
+	list[pos] = num; \
 	(pos)++; \
 } while(0)
 
@@ -281,17 +293,50 @@ gbox_picksplit(PG_FUNCTION_ARGS)
 	{
 		cur = DatumGetBoxP(((GISTENTRY *) VARDATA(entryvec))[i].key);
 		if (cur->low.x - pageunion.low.x < pageunion.high.x - cur->high.x)
-			ADDLIST(listL, unionL, posL);
+			ADDLIST(listL, unionL, posL,i);
 		else
-			ADDLIST(listR, unionR, posR);
+			ADDLIST(listR, unionR, posR,i);
 		if (cur->low.y - pageunion.low.y < pageunion.high.y - cur->high.y)
-			ADDLIST(listB, unionB, posB);
+			ADDLIST(listB, unionB, posB,i);
 		else
-			ADDLIST(listT, unionT, posT);
+			ADDLIST(listT, unionT, posT,i);
 	}
 
-	/* which split more optimal? */
+	/* bad disposition, sort by ascending and resplit */
+	if ( (posR==0 || posL==0) && (posT==0 || posB==0) ) {
+		KBsort *arr = (KBsort*)palloc( sizeof(KBsort) * maxoff );
+		posL = posR = posB = posT = 0;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i)) {
+			arr[i-1].key = DatumGetBoxP(((GISTENTRY *) VARDATA(entryvec))[i].key);
+			arr[i-1].pos = i;
+		}
+		qsort( arr, maxoff, sizeof(KBsort), compare_KB );
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i)) {
+			cur = arr[i-1].key;
+			if (cur->low.x - pageunion.low.x < pageunion.high.x - cur->high.x)
+				ADDLIST(listL, unionL, posL,arr[i-1].pos);
+			else if ( cur->low.x - pageunion.low.x == pageunion.high.x - cur->high.x ) {
+				if ( posL>posR )
+					ADDLIST(listR, unionR, posR,arr[i-1].pos);
+				else
+					ADDLIST(listL, unionL, posL,arr[i-1].pos);
+			} else
+				ADDLIST(listR, unionR, posR,arr[i-1].pos);
+
+			if (cur->low.y - pageunion.low.y < pageunion.high.y - cur->high.y)
+				ADDLIST(listB, unionB, posB,arr[i-1].pos);
+			else if ( cur->low.y - pageunion.low.y == pageunion.high.y - cur->high.y ) {
+				if ( posB>posT )
+					ADDLIST(listT, unionT, posT,arr[i-1].pos);
+				else
+					ADDLIST(listB, unionB, posB,arr[i-1].pos);
+			} else
+				ADDLIST(listT, unionT, posT,arr[i-1].pos);
+		}
+		pfree(arr);
+	}
 
+	/* which split more optimal? */
 	if (Max(posL, posR) < Max(posB, posT))
 		direction = 'x';
 	else if (Max(posL, posR) > Max(posB, posT))