Move ExecProcNode from dispatch to function pointer based model.

This allows us to add stack-depth checks the first time an executor
node is called, and skip that overhead on following
calls. Additionally it yields a nice speedup.

While it'd probably have been a good idea to have that check all
along, it has become more important after the new expression
evaluation framework in b8d7f053c5c2bf2a7e - there's no stack depth
check in common paths anymore now. We previously relied on
ExecEvalExpr() being executed somewhere.

We should move towards that model for further routines, but as this is
required for v10, it seems better to only do the necessary (which
already is quite large).

Author: Andres Freund, Tom Lane
Reported-By: Julien Rouhaud
Discussion:
    https://postgr.es/m/22833.1490390175@sss.pgh.pa.us
    https://postgr.es/m/b0af9eaa-130c-60d0-9e4e-7a135b1e0c76@dalibo.com

38 files changed, 35 insertions, 38 deletions

diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 59c28b709e..60326f9d03 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -225,14 +225,31 @@ extern void EvalPlanQualBegin(EPQState *epqstate, EState *parentestate);
 extern void EvalPlanQualEnd(EPQState *epqstate);
 
 /*
- * prototypes from functions in execProcnode.c
+ * functions in execProcnode.c
  */
 extern PlanState *ExecInitNode(Plan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecProcNode(PlanState *node);
 extern Node *MultiExecProcNode(PlanState *node);
 extern void ExecEndNode(PlanState *node);
 extern bool ExecShutdownNode(PlanState *node);
 
+
+/* ----------------------------------------------------------------
+ *		ExecProcNode
+ *
+ *		Execute the given node to return a(nother) tuple.
+ * ----------------------------------------------------------------
+ */
+#ifndef FRONTEND
+static inline TupleTableSlot *
+ExecProcNode(PlanState *node)
+{
+	if (node->chgParam != NULL) /* something changed? */
+		ExecReScan(node);		/* let ReScan handle this */
+
+	return node->ExecProcNode(node);
+}
+#endif
+
 /*
  * prototypes from functions in execExpr.c
  */
diff --git a/src/include/executor/nodeAgg.h b/src/include/executor/nodeAgg.h
index fa11ba93a6..eff5af9c2a 100644
--- a/src/include/executor/nodeAgg.h
+++ b/src/include/executor/nodeAgg.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern AggState *ExecInitAgg(Agg *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecAgg(AggState *node);
 extern void ExecEndAgg(AggState *node);
 extern void ExecReScanAgg(AggState *node);
 
diff --git a/src/include/executor/nodeAppend.h b/src/include/executor/nodeAppend.h
index ee0b6ad23d..4e38a1380e 100644
--- a/src/include/executor/nodeAppend.h
+++ b/src/include/executor/nodeAppend.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern AppendState *ExecInitAppend(Append *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecAppend(AppendState *node);
 extern void ExecEndAppend(AppendState *node);
 extern void ExecReScanAppend(AppendState *node);
 
diff --git a/src/include/executor/nodeBitmapHeapscan.h b/src/include/executor/nodeBitmapHeapscan.h
index f477d1c772..c77694cf22 100644
--- a/src/include/executor/nodeBitmapHeapscan.h
+++ b/src/include/executor/nodeBitmapHeapscan.h
@@ -18,7 +18,6 @@
 #include "access/parallel.h"
 
 extern BitmapHeapScanState *ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecBitmapHeapScan(BitmapHeapScanState *node);
 extern void ExecEndBitmapHeapScan(BitmapHeapScanState *node);
 extern void ExecReScanBitmapHeapScan(BitmapHeapScanState *node);
 extern void ExecBitmapHeapEstimate(BitmapHeapScanState *node,
diff --git a/src/include/executor/nodeCtescan.h b/src/include/executor/nodeCtescan.h
index 397bdfdd1c..d2fbcbd586 100644
--- a/src/include/executor/nodeCtescan.h
+++ b/src/include/executor/nodeCtescan.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern CteScanState *ExecInitCteScan(CteScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecCteScan(CteScanState *node);
 extern void ExecEndCteScan(CteScanState *node);
 extern void ExecReScanCteScan(CteScanState *node);
 
diff --git a/src/include/executor/nodeCustom.h b/src/include/executor/nodeCustom.h
index e81bcf7f21..a1cc63ae1f 100644
--- a/src/include/executor/nodeCustom.h
+++ b/src/include/executor/nodeCustom.h
@@ -21,7 +21,6 @@
  */
 extern CustomScanState *ExecInitCustomScan(CustomScan *custom_scan,
 				   EState *estate, int eflags);
-extern TupleTableSlot *ExecCustomScan(CustomScanState *node);
 extern void ExecEndCustomScan(CustomScanState *node);
 
 extern void ExecReScanCustomScan(CustomScanState *node);
diff --git a/src/include/executor/nodeForeignscan.h b/src/include/executor/nodeForeignscan.h
index 3ff4ecd8c9..0b662597d8 100644
--- a/src/include/executor/nodeForeignscan.h
+++ b/src/include/executor/nodeForeignscan.h
@@ -18,7 +18,6 @@
 #include "nodes/execnodes.h"
 
 extern ForeignScanState *ExecInitForeignScan(ForeignScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecForeignScan(ForeignScanState *node);
 extern void ExecEndForeignScan(ForeignScanState *node);
 extern void ExecReScanForeignScan(ForeignScanState *node);
 
diff --git a/src/include/executor/nodeFunctionscan.h b/src/include/executor/nodeFunctionscan.h
index 5e830ebdea..aaa9d8c316 100644
--- a/src/include/executor/nodeFunctionscan.h
+++ b/src/include/executor/nodeFunctionscan.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern FunctionScanState *ExecInitFunctionScan(FunctionScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecFunctionScan(FunctionScanState *node);
 extern void ExecEndFunctionScan(FunctionScanState *node);
 extern void ExecReScanFunctionScan(FunctionScanState *node);
 
diff --git a/src/include/executor/nodeGather.h b/src/include/executor/nodeGather.h
index b0006934d4..189bd70041 100644
--- a/src/include/executor/nodeGather.h
+++ b/src/include/executor/nodeGather.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern GatherState *ExecInitGather(Gather *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecGather(GatherState *node);
 extern void ExecEndGather(GatherState *node);
 extern void ExecShutdownGather(GatherState *node);
 extern void ExecReScanGather(GatherState *node);
diff --git a/src/include/executor/nodeGatherMerge.h b/src/include/executor/nodeGatherMerge.h
index 14b31a086c..0154d73312 100644
--- a/src/include/executor/nodeGatherMerge.h
+++ b/src/include/executor/nodeGatherMerge.h
@@ -19,7 +19,6 @@
 extern GatherMergeState *ExecInitGatherMerge(GatherMerge *node,
 					EState *estate,
 					int eflags);
-extern TupleTableSlot *ExecGatherMerge(GatherMergeState *node);
 extern void ExecEndGatherMerge(GatherMergeState *node);
 extern void ExecReScanGatherMerge(GatherMergeState *node);
 extern void ExecShutdownGatherMerge(GatherMergeState *node);
diff --git a/src/include/executor/nodeGroup.h b/src/include/executor/nodeGroup.h
index 7358b61707..b0d7e312c9 100644
--- a/src/include/executor/nodeGroup.h
+++ b/src/include/executor/nodeGroup.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern GroupState *ExecInitGroup(Group *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecGroup(GroupState *node);
 extern void ExecEndGroup(GroupState *node);
 extern void ExecReScanGroup(GroupState *node);
 
diff --git a/src/include/executor/nodeHash.h b/src/include/executor/nodeHash.h
index 8052f27d0b..3ae556fb6c 100644
--- a/src/include/executor/nodeHash.h
+++ b/src/include/executor/nodeHash.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern HashState *ExecInitHash(Hash *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecHash(HashState *node);
 extern Node *MultiExecHash(HashState *node);
 extern void ExecEndHash(HashState *node);
 extern void ExecReScanHash(HashState *node);
diff --git a/src/include/executor/nodeHashjoin.h b/src/include/executor/nodeHashjoin.h
index 541c81edc7..7469bfbf60 100644
--- a/src/include/executor/nodeHashjoin.h
+++ b/src/include/executor/nodeHashjoin.h
@@ -18,7 +18,6 @@
 #include "storage/buffile.h"
 
 extern HashJoinState *ExecInitHashJoin(HashJoin *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecHashJoin(HashJoinState *node);
 extern void ExecEndHashJoin(HashJoinState *node);
 extern void ExecReScanHashJoin(HashJoinState *node);
 
diff --git a/src/include/executor/nodeIndexonlyscan.h b/src/include/executor/nodeIndexonlyscan.h
index cf227daae0..c8a709c26e 100644
--- a/src/include/executor/nodeIndexonlyscan.h
+++ b/src/include/executor/nodeIndexonlyscan.h
@@ -18,7 +18,6 @@
 #include "access/parallel.h"
 
 extern IndexOnlyScanState *ExecInitIndexOnlyScan(IndexOnlyScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecIndexOnlyScan(IndexOnlyScanState *node);
 extern void ExecEndIndexOnlyScan(IndexOnlyScanState *node);
 extern void ExecIndexOnlyMarkPos(IndexOnlyScanState *node);
 extern void ExecIndexOnlyRestrPos(IndexOnlyScanState *node);
diff --git a/src/include/executor/nodeIndexscan.h b/src/include/executor/nodeIndexscan.h
index 0118234eca..1668e347ee 100644
--- a/src/include/executor/nodeIndexscan.h
+++ b/src/include/executor/nodeIndexscan.h
@@ -18,7 +18,6 @@
 #include "nodes/execnodes.h"
 
 extern IndexScanState *ExecInitIndexScan(IndexScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecIndexScan(IndexScanState *node);
 extern void ExecEndIndexScan(IndexScanState *node);
 extern void ExecIndexMarkPos(IndexScanState *node);
 extern void ExecIndexRestrPos(IndexScanState *node);
diff --git a/src/include/executor/nodeLimit.h b/src/include/executor/nodeLimit.h
index 7bb20d9978..db65b5524c 100644
--- a/src/include/executor/nodeLimit.h
+++ b/src/include/executor/nodeLimit.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern LimitState *ExecInitLimit(Limit *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecLimit(LimitState *node);
 extern void ExecEndLimit(LimitState *node);
 extern void ExecReScanLimit(LimitState *node);
 
diff --git a/src/include/executor/nodeLockRows.h b/src/include/executor/nodeLockRows.h
index 6b90756e4c..c9d05b87f1 100644
--- a/src/include/executor/nodeLockRows.h
+++ b/src/include/executor/nodeLockRows.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern LockRowsState *ExecInitLockRows(LockRows *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecLockRows(LockRowsState *node);
 extern void ExecEndLockRows(LockRowsState *node);
 extern void ExecReScanLockRows(LockRowsState *node);
 
diff --git a/src/include/executor/nodeMaterial.h b/src/include/executor/nodeMaterial.h
index f69abbca82..4b3c2578c9 100644
--- a/src/include/executor/nodeMaterial.h
+++ b/src/include/executor/nodeMaterial.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern MaterialState *ExecInitMaterial(Material *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecMaterial(MaterialState *node);
 extern void ExecEndMaterial(MaterialState *node);
 extern void ExecMaterialMarkPos(MaterialState *node);
 extern void ExecMaterialRestrPos(MaterialState *node);
diff --git a/src/include/executor/nodeMergeAppend.h b/src/include/executor/nodeMergeAppend.h
index 3cc6ef549b..a0ccbae965 100644
--- a/src/include/executor/nodeMergeAppend.h
+++ b/src/include/executor/nodeMergeAppend.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern MergeAppendState *ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecMergeAppend(MergeAppendState *node);
 extern void ExecEndMergeAppend(MergeAppendState *node);
 extern void ExecReScanMergeAppend(MergeAppendState *node);
 
diff --git a/src/include/executor/nodeMergejoin.h b/src/include/executor/nodeMergejoin.h
index 32df25ae8b..d20e41505d 100644
--- a/src/include/executor/nodeMergejoin.h
+++ b/src/include/executor/nodeMergejoin.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern MergeJoinState *ExecInitMergeJoin(MergeJoin *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecMergeJoin(MergeJoinState *node);
 extern void ExecEndMergeJoin(MergeJoinState *node);
 extern void ExecReScanMergeJoin(MergeJoinState *node);
 
diff --git a/src/include/executor/nodeModifyTable.h b/src/include/executor/nodeModifyTable.h
index 5a406f236d..a2e7af98de 100644
--- a/src/include/executor/nodeModifyTable.h
+++ b/src/include/executor/nodeModifyTable.h
@@ -16,7 +16,6 @@
 #include "nodes/execnodes.h"
 
 extern ModifyTableState *ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecModifyTable(ModifyTableState *node);
 extern void ExecEndModifyTable(ModifyTableState *node);
 extern void ExecReScanModifyTable(ModifyTableState *node);
 
diff --git a/src/include/executor/nodeNamedtuplestorescan.h b/src/include/executor/nodeNamedtuplestorescan.h
index 7f72fbe98a..395d978f62 100644
--- a/src/include/executor/nodeNamedtuplestorescan.h
+++ b/src/include/executor/nodeNamedtuplestorescan.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern NamedTuplestoreScanState *ExecInitNamedTuplestoreScan(NamedTuplestoreScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecNamedTuplestoreScan(NamedTuplestoreScanState *node);
 extern void ExecEndNamedTuplestoreScan(NamedTuplestoreScanState *node);
 extern void ExecReScanNamedTuplestoreScan(NamedTuplestoreScanState *node);
 
diff --git a/src/include/executor/nodeNestloop.h b/src/include/executor/nodeNestloop.h
index 8e0fcc1922..0d6486cc57 100644
--- a/src/include/executor/nodeNestloop.h
+++ b/src/include/executor/nodeNestloop.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern NestLoopState *ExecInitNestLoop(NestLoop *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecNestLoop(NestLoopState *node);
 extern void ExecEndNestLoop(NestLoopState *node);
 extern void ExecReScanNestLoop(NestLoopState *node);
 
diff --git a/src/include/executor/nodeProjectSet.h b/src/include/executor/nodeProjectSet.h
index 2f6999e8db..a0b0521f8d 100644
--- a/src/include/executor/nodeProjectSet.h
+++ b/src/include/executor/nodeProjectSet.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern ProjectSetState *ExecInitProjectSet(ProjectSet *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecProjectSet(ProjectSetState *node);
 extern void ExecEndProjectSet(ProjectSetState *node);
 extern void ExecReScanProjectSet(ProjectSetState *node);
 
diff --git a/src/include/executor/nodeRecursiveunion.h b/src/include/executor/nodeRecursiveunion.h
index f0eba05bee..e6ce1b4783 100644
--- a/src/include/executor/nodeRecursiveunion.h
+++ b/src/include/executor/nodeRecursiveunion.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern RecursiveUnionState *ExecInitRecursiveUnion(RecursiveUnion *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecRecursiveUnion(RecursiveUnionState *node);
 extern void ExecEndRecursiveUnion(RecursiveUnionState *node);
 extern void ExecReScanRecursiveUnion(RecursiveUnionState *node);
 
diff --git a/src/include/executor/nodeResult.h b/src/include/executor/nodeResult.h
index 61d3cb2cc2..20e0063410 100644
--- a/src/include/executor/nodeResult.h
+++ b/src/include/executor/nodeResult.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern ResultState *ExecInitResult(Result *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecResult(ResultState *node);
 extern void ExecEndResult(ResultState *node);
 extern void ExecResultMarkPos(ResultState *node);
 extern void ExecResultRestrPos(ResultState *node);
diff --git a/src/include/executor/nodeSamplescan.h b/src/include/executor/nodeSamplescan.h
index ed06e77e4e..607bbd9412 100644
--- a/src/include/executor/nodeSamplescan.h
+++ b/src/include/executor/nodeSamplescan.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern SampleScanState *ExecInitSampleScan(SampleScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecSampleScan(SampleScanState *node);
 extern void ExecEndSampleScan(SampleScanState *node);
 extern void ExecReScanSampleScan(SampleScanState *node);
 
diff --git a/src/include/executor/nodeSeqscan.h b/src/include/executor/nodeSeqscan.h
index 06e0686b0b..0fba79f8de 100644
--- a/src/include/executor/nodeSeqscan.h
+++ b/src/include/executor/nodeSeqscan.h
@@ -18,7 +18,6 @@
 #include "nodes/execnodes.h"
 
 extern SeqScanState *ExecInitSeqScan(SeqScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecSeqScan(SeqScanState *node);
 extern void ExecEndSeqScan(SeqScanState *node);
 extern void ExecReScanSeqScan(SeqScanState *node);
 
diff --git a/src/include/executor/nodeSetOp.h b/src/include/executor/nodeSetOp.h
index af85977183..c15f945046 100644
--- a/src/include/executor/nodeSetOp.h
+++ b/src/include/executor/nodeSetOp.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern SetOpState *ExecInitSetOp(SetOp *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecSetOp(SetOpState *node);
 extern void ExecEndSetOp(SetOpState *node);
 extern void ExecReScanSetOp(SetOpState *node);
 
diff --git a/src/include/executor/nodeSort.h b/src/include/executor/nodeSort.h
index 1d2b7130b3..ed0e9dbb53 100644
--- a/src/include/executor/nodeSort.h
+++ b/src/include/executor/nodeSort.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern SortState *ExecInitSort(Sort *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecSort(SortState *node);
 extern void ExecEndSort(SortState *node);
 extern void ExecSortMarkPos(SortState *node);
 extern void ExecSortRestrPos(SortState *node);
diff --git a/src/include/executor/nodeSubqueryscan.h b/src/include/executor/nodeSubqueryscan.h
index c852e2947f..710e050285 100644
--- a/src/include/executor/nodeSubqueryscan.h
+++ b/src/include/executor/nodeSubqueryscan.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern SubqueryScanState *ExecInitSubqueryScan(SubqueryScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecSubqueryScan(SubqueryScanState *node);
 extern void ExecEndSubqueryScan(SubqueryScanState *node);
 extern void ExecReScanSubqueryScan(SubqueryScanState *node);
 
diff --git a/src/include/executor/nodeTableFuncscan.h b/src/include/executor/nodeTableFuncscan.h
index c58156e99c..c4672c0ac0 100644
--- a/src/include/executor/nodeTableFuncscan.h
+++ b/src/include/executor/nodeTableFuncscan.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern TableFuncScanState *ExecInitTableFuncScan(TableFuncScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecTableFuncScan(TableFuncScanState *node);
 extern void ExecEndTableFuncScan(TableFuncScanState *node);
 extern void ExecReScanTableFuncScan(TableFuncScanState *node);
 
diff --git a/src/include/executor/nodeTidscan.h b/src/include/executor/nodeTidscan.h
index d07ed7c864..e68aaf3829 100644
--- a/src/include/executor/nodeTidscan.h
+++ b/src/include/executor/nodeTidscan.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern TidScanState *ExecInitTidScan(TidScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecTidScan(TidScanState *node);
 extern void ExecEndTidScan(TidScanState *node);
 extern void ExecReScanTidScan(TidScanState *node);
 
diff --git a/src/include/executor/nodeUnique.h b/src/include/executor/nodeUnique.h
index 3d0ac9dde1..008774ae0f 100644
--- a/src/include/executor/nodeUnique.h
+++ b/src/include/executor/nodeUnique.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern UniqueState *ExecInitUnique(Unique *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecUnique(UniqueState *node);
 extern void ExecEndUnique(UniqueState *node);
 extern void ExecReScanUnique(UniqueState *node);
 
diff --git a/src/include/executor/nodeValuesscan.h b/src/include/executor/nodeValuesscan.h
index c28bb1acce..772a5e9705 100644
--- a/src/include/executor/nodeValuesscan.h
+++ b/src/include/executor/nodeValuesscan.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern ValuesScanState *ExecInitValuesScan(ValuesScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecValuesScan(ValuesScanState *node);
 extern void ExecEndValuesScan(ValuesScanState *node);
 extern void ExecReScanValuesScan(ValuesScanState *node);
 
diff --git a/src/include/executor/nodeWindowAgg.h b/src/include/executor/nodeWindowAgg.h
index db1ad60677..1c177309ae 100644
--- a/src/include/executor/nodeWindowAgg.h
+++ b/src/include/executor/nodeWindowAgg.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern WindowAggState *ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecWindowAgg(WindowAggState *node);
 extern void ExecEndWindowAgg(WindowAggState *node);
 extern void ExecReScanWindowAgg(WindowAggState *node);
 
diff --git a/src/include/executor/nodeWorktablescan.h b/src/include/executor/nodeWorktablescan.h
index c222d9f6b4..df05e75111 100644
--- a/src/include/executor/nodeWorktablescan.h
+++ b/src/include/executor/nodeWorktablescan.h
@@ -17,7 +17,6 @@
 #include "nodes/execnodes.h"
 
 extern WorkTableScanState *ExecInitWorkTableScan(WorkTableScan *node, EState *estate, int eflags);
-extern TupleTableSlot *ExecWorkTableScan(WorkTableScanState *node);
 extern void ExecEndWorkTableScan(WorkTableScanState *node);
 extern void ExecReScanWorkTableScan(WorkTableScanState *node);
 
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 85fac8ab91..35c28a6143 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -818,6 +818,18 @@ typedef struct DomainConstraintState
  * ----------------------------------------------------------------
  */
 
+struct PlanState;
+
+/* ----------------
+ *	 ExecProcNodeMtd
+ *
+ * This is the method called by ExecProcNode to return the next tuple
+ * from an executor node.  It returns NULL, or an empty TupleTableSlot,
+ * if no more tuples are available.
+ * ----------------
+ */
+typedef TupleTableSlot *(*ExecProcNodeMtd) (struct PlanState *pstate);
+
 /* ----------------
  *		PlanState node
  *
@@ -835,6 +847,10 @@ typedef struct PlanState
 								 * nodes point to one EState for the whole
 								 * top-level plan */
 
+	ExecProcNodeMtd ExecProcNode;	/* function to return next tuple */
+	ExecProcNodeMtd ExecProcNodeReal;	/* actual function, if above is a
+										 * wrapper */
+
 	Instrumentation *instrument;	/* Optional runtime stats for this node */
 	WorkerInstrumentation *worker_instrument;	/* per-worker instrumentation */