Use outerPlanState macro instead of referring to leffttree.

This makes the executor code more consistent.  It also removes
an apparently superfluous NULL test in nodeGroup.c.

Qingqing Zhou, reviewed by Tom Lane, and further revised by me.

src/backend/executor/nodeAgg.c

@@ -2053,6 +2053,7 @@ void
 ExecReScanAgg(AggState *node)
 {
 	ExprContext *econtext = node->ss.ps.ps_ExprContext;
+	PlanState	*outerPlan = outerPlanState(node);
 	int			aggno;
 
 	node->agg_done = false;
@@ -2075,7 +2076,7 @@ ExecReScanAgg(AggState *node)
 		 * parameter changes, then we can just rescan the existing hash table;
 		 * no need to build it again.
 		 */
-		if (node->ss.ps.lefttree->chgParam == NULL)
+		if (outerPlan->chgParam == NULL)
 		{
 			ResetTupleHashIterator(node->hashtable, &node->hashiter);
 			return;
@@ -2133,8 +2134,8 @@ ExecReScanAgg(AggState *node)
 	 * if chgParam of subnode is not null then plan will be re-scanned by
 	 * first ExecProcNode.
 	 */
-	if (node->ss.ps.lefttree->chgParam == NULL)
-		ExecReScan(node->ss.ps.lefttree);
+	if (outerPlan->chgParam == NULL)
+		ExecReScan(outerPlan);
 }
 
 

src/backend/executor/nodeBitmapHeapscan.c

@@ -449,6 +449,8 @@ ExecBitmapHeapScan(BitmapHeapScanState *node)
 void
 ExecReScanBitmapHeapScan(BitmapHeapScanState *node)
 {
+	PlanState	*outerPlan = outerPlanState(node);
+
 	/* rescan to release any page pin */
 	heap_rescan(node->ss.ss_currentScanDesc, NULL);
 
@@ -469,8 +471,8 @@ ExecReScanBitmapHeapScan(BitmapHeapScanState *node)
 	 * if chgParam of subnode is not null then plan will be re-scanned by
 	 * first ExecProcNode.
 	 */
-	if (node->ss.ps.lefttree->chgParam == NULL)
-		ExecReScan(node->ss.ps.lefttree);
+	if (outerPlan->chgParam == NULL)
+		ExecReScan(outerPlan);
 }
 
 /* ----------------------------------------------------------------

src/backend/executor/nodeGroup.c

@@ -280,6 +280,8 @@ ExecEndGroup(GroupState *node)
 void
 ExecReScanGroup(GroupState *node)
 {
+	PlanState	*outerPlan = outerPlanState(node);
+
 	node->grp_done = FALSE;
 	node->ss.ps.ps_TupFromTlist = false;
 	/* must clear first tuple */
@@ -289,7 +291,6 @@ ExecReScanGroup(GroupState *node)
 	 * if chgParam of subnode is not null then plan will be re-scanned by
 	 * first ExecProcNode.
 	 */
-	if (node->ss.ps.lefttree &&
-		node->ss.ps.lefttree->chgParam == NULL)
-		ExecReScan(node->ss.ps.lefttree);
+	if (outerPlan->chgParam == NULL)
+		ExecReScan(outerPlan);
 }

src/backend/executor/nodeMaterial.c

@@ -317,6 +317,8 @@ ExecMaterialRestrPos(MaterialState *node)
 void
 ExecReScanMaterial(MaterialState *node)
 {
+	PlanState	*outerPlan = outerPlanState(node);
+
 	ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
 
 	if (node->eflags != 0)
@@ -339,13 +341,13 @@ ExecReScanMaterial(MaterialState *node)
 		 * Otherwise we can just rewind and rescan the stored output. The
 		 * state of the subnode does not change.
 		 */
-		if (node->ss.ps.lefttree->chgParam != NULL ||
+		if (outerPlan->chgParam != NULL ||
 			(node->eflags & EXEC_FLAG_REWIND) == 0)
 		{
 			tuplestore_end(node->tuplestorestate);
 			node->tuplestorestate = NULL;
-			if (node->ss.ps.lefttree->chgParam == NULL)
-				ExecReScan(node->ss.ps.lefttree);
+			if (outerPlan->chgParam == NULL)
+				ExecReScan(outerPlan);
 			node->eof_underlying = false;
 		}
 		else
@@ -359,8 +361,8 @@ ExecReScanMaterial(MaterialState *node)
 		 * if chgParam of subnode is not null then plan will be re-scanned by
 		 * first ExecProcNode.
 		 */
-		if (node->ss.ps.lefttree->chgParam == NULL)
-			ExecReScan(node->ss.ps.lefttree);
+		if (outerPlan->chgParam == NULL)
+			ExecReScan(outerPlan);
 		node->eof_underlying = false;
 	}
 }

src/backend/executor/nodeSort.c

@@ -290,6 +290,8 @@ ExecSortRestrPos(SortState *node)
 void
 ExecReScanSort(SortState *node)
 {
+	PlanState	*outerPlan = outerPlanState(node);
+
 	/*
 	 * If we haven't sorted yet, just return. If outerplan's chgParam is not
 	 * NULL then it will be re-scanned by ExecProcNode, else no reason to
@@ -308,7 +310,7 @@ ExecReScanSort(SortState *node)
 	 *
 	 * Otherwise we can just rewind and rescan the sorted output.
 	 */
-	if (node->ss.ps.lefttree->chgParam != NULL ||
+	if (outerPlan->chgParam != NULL ||
 		node->bounded != node->bounded_Done ||
 		node->bound != node->bound_Done ||
 		!node->randomAccess)
@@ -321,8 +323,8 @@ ExecReScanSort(SortState *node)
 		 * if chgParam of subnode is not null then plan will be re-scanned by
 		 * first ExecProcNode.
 		 */
-		if (node->ss.ps.lefttree->chgParam == NULL)
-			ExecReScan(node->ss.ps.lefttree);
+		if (outerPlan->chgParam == NULL)
+			ExecReScan(outerPlan);
 	}
 	else
 		tuplesort_rescan((Tuplesortstate *) node->tuplesortstate);

src/backend/executor/nodeWindowAgg.c

@@ -2057,6 +2057,7 @@ ExecEndWindowAgg(WindowAggState *node)
 void
 ExecReScanWindowAgg(WindowAggState *node)
 {
+	PlanState	*outerPlan = outerPlanState(node);
 	ExprContext *econtext = node->ss.ps.ps_ExprContext;
 
 	node->all_done = false;
@@ -2082,8 +2083,8 @@ ExecReScanWindowAgg(WindowAggState *node)
 	 * if chgParam of subnode is not null then plan will be re-scanned by
 	 * first ExecProcNode.
 	 */
-	if (node->ss.ps.lefttree->chgParam == NULL)
-		ExecReScan(node->ss.ps.lefttree);
+	if (outerPlan->chgParam == NULL)
+		ExecReScan(outerPlan);
 }
 
 /*