From ddaa761e96cd4b34035edd40f6bc17b953574496 Mon Sep 17 00:00:00 2001
From: Amit Langote <amitlan@postgresql.org>
Date: Fri, 11 Aug 2023 14:09:29 +0900
Subject: [PATCH v45 1/6] Add support for allowing ExecInitNode to detect
 CachedPlan invalidation

This means ExecInitNode() will check for CachedPlan invalidation at
various points (after locking tables, initializing child plans, etc.)
and return either a partially initialized planstate node or NULL if
no cleanup is necessary.

ExecEndNode() subroutines now always check a pointer for nullness
before calling cleanup on it.
---
 contrib/postgres_fdw/postgres_fdw.c           |  4 ++++
 src/backend/executor/execMain.c               | 23 +++++++++++++++++--
 src/backend/executor/execPartition.c          |  4 ++++
 src/backend/executor/execProcnode.c           | 12 +++++++++-
 src/backend/executor/execUtils.c              |  2 ++
 src/backend/executor/nodeAgg.c                | 15 ++++--------
 src/backend/executor/nodeAppend.c             | 10 +++++---
 src/backend/executor/nodeBitmapAnd.c          |  7 +++---
 src/backend/executor/nodeBitmapHeapscan.c     | 19 +++++----------
 src/backend/executor/nodeBitmapIndexscan.c    | 10 ++------
 src/backend/executor/nodeBitmapOr.c           |  7 +++---
 src/backend/executor/nodeCtescan.c            | 12 ----------
 src/backend/executor/nodeCustom.c             | 16 ++++++-------
 src/backend/executor/nodeForeignscan.c        | 12 ++++------
 src/backend/executor/nodeFunctionscan.c       | 12 ----------
 src/backend/executor/nodeGather.c             |  6 ++---
 src/backend/executor/nodeGatherMerge.c        |  5 ++--
 src/backend/executor/nodeGroup.c              |  7 ++----
 src/backend/executor/nodeHash.c               |  7 ++----
 src/backend/executor/nodeHashjoin.c           | 16 ++++---------
 src/backend/executor/nodeIncrementalSort.c    | 10 ++------
 src/backend/executor/nodeIndexonlyscan.c      | 20 ++++------------
 src/backend/executor/nodeIndexscan.c          | 20 ++++------------
 src/backend/executor/nodeLimit.c              |  3 ++-
 src/backend/executor/nodeLockRows.c           |  2 ++
 src/backend/executor/nodeMaterial.c           |  7 ++----
 src/backend/executor/nodeMemoize.c            | 12 +++-------
 src/backend/executor/nodeMergeAppend.c        |  6 ++++-
 src/backend/executor/nodeMergejoin.c          | 16 ++++---------
 src/backend/executor/nodeModifyTable.c        | 18 ++++++---------
 .../executor/nodeNamedtuplestorescan.c        | 11 ---------
 src/backend/executor/nodeNestloop.c           | 15 ++++--------
 src/backend/executor/nodeProjectSet.c         | 12 ++--------
 src/backend/executor/nodeRecursiveunion.c     | 10 ++++++--
 src/backend/executor/nodeResult.c             | 12 ++--------
 src/backend/executor/nodeSamplescan.c         | 16 +++----------
 src/backend/executor/nodeSeqscan.c            | 14 ++---------
 src/backend/executor/nodeSetOp.c              |  6 ++---
 src/backend/executor/nodeSort.c               |  9 ++------
 src/backend/executor/nodeSubqueryscan.c       | 14 ++---------
 src/backend/executor/nodeTableFuncscan.c      | 12 ----------
 src/backend/executor/nodeTidrangescan.c       | 14 ++---------
 src/backend/executor/nodeTidscan.c            | 14 ++---------
 src/backend/executor/nodeUnique.c             |  7 ++----
 src/backend/executor/nodeValuesscan.c         | 13 -----------
 src/backend/executor/nodeWindowAgg.c          | 13 ++---------
 src/backend/executor/nodeWorktablescan.c      | 11 ---------
 src/include/executor/executor.h               | 12 ++++++++++
 src/include/nodes/execnodes.h                 |  2 ++
 src/include/utils/plancache.h                 | 14 +++++++++++
 50 files changed, 191 insertions(+), 360 deletions(-)

diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index c5cada55fb..1edd4c3f17 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -2658,7 +2658,11 @@ postgresBeginDirectModify(ForeignScanState *node, int eflags)
 	/* Get info about foreign table. */
 	rtindex = node->resultRelInfo->ri_RangeTableIndex;
 	if (fsplan->scan.scanrelid == 0)
+	{
 		dmstate->rel = ExecOpenScanRelation(estate, rtindex, eflags);
+		if (!ExecPlanStillValid(estate))
+			return;
+	}
 	else
 		dmstate->rel = node->ss.ss_currentRelation;
 	table = GetForeignTable(RelationGetRelid(dmstate->rel));
diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 4c5a7bbf62..1a848b1c20 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -839,7 +839,7 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 	Plan	   *plan = plannedstmt->planTree;
 	List	   *rangeTable = plannedstmt->rtable;
 	EState	   *estate = queryDesc->estate;
-	PlanState  *planstate;
+	PlanState  *planstate = NULL;
 	TupleDesc	tupType;
 	ListCell   *l;
 	int			i;
@@ -855,6 +855,7 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 	ExecInitRangeTable(estate, rangeTable, plannedstmt->permInfos);
 
 	estate->es_plannedstmt = plannedstmt;
+	estate->es_cachedplan = NULL;
 
 	/*
 	 * Next, build the ExecRowMark array from the PlanRowMark(s), if any.
@@ -886,6 +887,8 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 				case ROW_MARK_KEYSHARE:
 				case ROW_MARK_REFERENCE:
 					relation = ExecGetRangeTableRelation(estate, rc->rti);
+					if (!ExecPlanStillValid(estate))
+						goto plan_init_suspended;
 					break;
 				case ROW_MARK_COPY:
 					/* no physical table access is required */
@@ -953,9 +956,10 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 			sp_eflags |= EXEC_FLAG_REWIND;
 
 		subplanstate = ExecInitNode(subplan, estate, sp_eflags);
-
 		estate->es_subplanstates = lappend(estate->es_subplanstates,
 										   subplanstate);
+		if (!ExecPlanStillValid(estate))
+			goto plan_init_suspended;
 
 		i++;
 	}
@@ -966,6 +970,8 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 	 * processing tuples.
 	 */
 	planstate = ExecInitNode(plan, estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		goto plan_init_suspended;
 
 	/*
 	 * Get the tuple descriptor describing the type of tuples to return.
@@ -1008,6 +1014,15 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 	}
 
 	queryDesc->tupDesc = tupType;
+	Assert(planstate != NULL);
+	queryDesc->planstate = planstate;
+	return;
+
+plan_init_suspended:
+	/*
+	 * Plan initialization failed.  Mark QueryDesc as such.  ExecEndPlan()
+	 * will clean up initialized plan nodes from estate->es_planstate_nodes.
+	 */
 	queryDesc->planstate = planstate;
 }
 
@@ -3010,6 +3025,10 @@ EvalPlanQualEnd(EPQState *epqstate)
 	MemoryContext oldcontext;
 	ListCell   *l;
 
+	/* Nothing to do if EvalPlanQualInit() wasn't done to begin with. */
+	if (epqstate->parentestate == NULL)
+		return;
+
 	rtsize = epqstate->parentestate->es_range_table_size;
 
 	/*
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index eb8a87fd63..e88455368c 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -1801,6 +1801,8 @@ ExecInitPartitionPruning(PlanState *planstate,
 
 	/* Create the working data structure for pruning */
 	prunestate = CreatePartitionPruneState(planstate, pruneinfo);
+	if (!ExecPlanStillValid(estate))
+		return NULL;
 
 	/*
 	 * Perform an initial partition prune pass, if required.
@@ -1927,6 +1929,8 @@ CreatePartitionPruneState(PlanState *planstate, PartitionPruneInfo *pruneinfo)
 			 * duration of this executor run.
 			 */
 			partrel = ExecGetRangeTableRelation(estate, pinfo->rtindex);
+			if (!ExecPlanStillValid(estate))
+				return NULL;
 			partkey = RelationGetPartitionKey(partrel);
 			partdesc = PartitionDirectoryLookup(estate->es_partition_directory,
 												partrel);
diff --git a/src/backend/executor/execProcnode.c b/src/backend/executor/execProcnode.c
index 4d288bc8d4..842c6751c5 100644
--- a/src/backend/executor/execProcnode.c
+++ b/src/backend/executor/execProcnode.c
@@ -135,7 +135,13 @@ static bool ExecShutdownNode_walker(PlanState *node, void *context);
  *		  'estate' is the shared execution state for the plan tree
  *		  'eflags' is a bitwise OR of flag bits described in executor.h
  *
- *		Returns a PlanState node corresponding to the given Plan node.
+ *		Returns a PlanState node corresponding to the given Plan node or NULL.
+ *
+ *		NULL may be returned either if the input node is NULL or if the plan
+ *		tree that the node is a part of is found to have been invalidated when
+ *		taking a lock on the relation mentioned in the node or in a child
+ *		node.  The latter case arises if the plan tree contains inheritance/
+ *		partition child tables and is from a CachedPlan.
  * ------------------------------------------------------------------------
  */
 PlanState *
@@ -388,6 +394,10 @@ ExecInitNode(Plan *node, EState *estate, int eflags)
 			break;
 	}
 
+	if (!ExecPlanStillValid(estate))
+		return result;
+
+	Assert(result != NULL);
 	ExecSetExecProcNode(result, result->ExecProcNode);
 
 	/*
diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c
index c06b228858..f4611bdd27 100644
--- a/src/backend/executor/execUtils.c
+++ b/src/backend/executor/execUtils.c
@@ -848,6 +848,8 @@ ExecInitResultRelation(EState *estate, ResultRelInfo *resultRelInfo,
 	Relation	resultRelationDesc;
 
 	resultRelationDesc = ExecGetRangeTableRelation(estate, rti);
+	if (!ExecPlanStillValid(estate))
+		return;
 	InitResultRelInfo(resultRelInfo,
 					  resultRelationDesc,
 					  rti,
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 468db94fe5..f46c3df199 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -3150,7 +3150,8 @@ hashagg_reset_spill_state(AggState *aggstate)
 	}
 
 	/* free batches */
-	list_free_deep(aggstate->hash_batches);
+	if (aggstate->hash_batches)
+		list_free_deep(aggstate->hash_batches);
 	aggstate->hash_batches = NIL;
 
 	/* close tape set */
@@ -3304,6 +3305,8 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 		eflags &= ~EXEC_FLAG_REWIND;
 	outerPlan = outerPlan(node);
 	outerPlanState(aggstate) = ExecInitNode(outerPlan, estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return aggstate;
 
 	/*
 	 * initialize source tuple type.
@@ -4357,16 +4360,6 @@ ExecEndAgg(AggState *node)
 	if (node->hashcontext)
 		ReScanExprContext(node->hashcontext);
 
-	/*
-	 * We don't actually free any ExprContexts here (see comment in
-	 * ExecFreeExprContext), just unlinking the output one from the plan node
-	 * suffices.
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/* clean up tuple table */
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	outerPlan = outerPlanState(node);
 	ExecEndNode(outerPlan);
 }
diff --git a/src/backend/executor/nodeAppend.c b/src/backend/executor/nodeAppend.c
index 609df6b9e6..5d9fa4bff3 100644
--- a/src/backend/executor/nodeAppend.c
+++ b/src/backend/executor/nodeAppend.c
@@ -147,6 +147,8 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 											  list_length(node->appendplans),
 											  node->part_prune_info,
 											  &validsubplans);
+		if (!ExecPlanStillValid(estate))
+			return NULL;
 		appendstate->as_prune_state = prunestate;
 		nplans = bms_num_members(validsubplans);
 
@@ -185,8 +187,9 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 	appendstate->ps.resultopsset = true;
 	appendstate->ps.resultopsfixed = false;
 
-	appendplanstates = (PlanState **) palloc(nplans *
-											 sizeof(PlanState *));
+	appendstate->appendplans = appendplanstates =
+		(PlanState **) palloc0(nplans * sizeof(PlanState *));
+	appendstate->as_nplans = nplans;
 
 	/*
 	 * call ExecInitNode on each of the valid plans to be executed and save
@@ -221,11 +224,12 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
 			firstvalid = j;
 
 		appendplanstates[j++] = ExecInitNode(initNode, estate, eflags);
+		if (!ExecPlanStillValid(estate))
+			return appendstate;
 	}
 
 	appendstate->as_first_partial_plan = firstvalid;
 	appendstate->appendplans = appendplanstates;
-	appendstate->as_nplans = nplans;
 
 	/* Initialize async state */
 	appendstate->as_asyncplans = asyncplans;
diff --git a/src/backend/executor/nodeBitmapAnd.c b/src/backend/executor/nodeBitmapAnd.c
index 4c5eb2b23b..93e5de0c1a 100644
--- a/src/backend/executor/nodeBitmapAnd.c
+++ b/src/backend/executor/nodeBitmapAnd.c
@@ -78,7 +78,6 @@ ExecInitBitmapAnd(BitmapAnd *node, EState *estate, int eflags)
 	bitmapandstate->ps.state = estate;
 	bitmapandstate->ps.ExecProcNode = ExecBitmapAnd;
 	bitmapandstate->bitmapplans = bitmapplanstates;
-	bitmapandstate->nplans = nplans;
 
 	/*
 	 * call ExecInitNode on each of the plans to be executed and save the
@@ -88,8 +87,10 @@ ExecInitBitmapAnd(BitmapAnd *node, EState *estate, int eflags)
 	foreach(l, node->bitmapplans)
 	{
 		initNode = (Plan *) lfirst(l);
-		bitmapplanstates[i] = ExecInitNode(initNode, estate, eflags);
-		i++;
+		bitmapplanstates[i++] = ExecInitNode(initNode, estate, eflags);
+		if (!ExecPlanStillValid(estate))
+			return bitmapandstate;
+		bitmapandstate->nplans = i;
 	}
 
 	/*
diff --git a/src/backend/executor/nodeBitmapHeapscan.c b/src/backend/executor/nodeBitmapHeapscan.c
index f35df0b8bf..3cdece852c 100644
--- a/src/backend/executor/nodeBitmapHeapscan.c
+++ b/src/backend/executor/nodeBitmapHeapscan.c
@@ -655,18 +655,6 @@ ExecEndBitmapHeapScan(BitmapHeapScanState *node)
 	 */
 	scanDesc = node->ss.ss_currentScanDesc;
 
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clear out tuple table slots
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	/*
 	 * close down subplans
 	 */
@@ -693,7 +681,8 @@ ExecEndBitmapHeapScan(BitmapHeapScanState *node)
 	/*
 	 * close heap scan
 	 */
-	table_endscan(scanDesc);
+	if (scanDesc)
+		table_endscan(scanDesc);
 }
 
 /* ----------------------------------------------------------------
@@ -763,11 +752,15 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags)
 	 * open the scan relation
 	 */
 	currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
+	if (!ExecPlanStillValid(estate))
+		return scanstate;
 
 	/*
 	 * initialize child nodes
 	 */
 	outerPlanState(scanstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return scanstate;
 
 	/*
 	 * get the scan type from the relation descriptor.
diff --git a/src/backend/executor/nodeBitmapIndexscan.c b/src/backend/executor/nodeBitmapIndexscan.c
index 83ec9ede89..4200472d02 100644
--- a/src/backend/executor/nodeBitmapIndexscan.c
+++ b/src/backend/executor/nodeBitmapIndexscan.c
@@ -184,14 +184,6 @@ ExecEndBitmapIndexScan(BitmapIndexScanState *node)
 	indexRelationDesc = node->biss_RelationDesc;
 	indexScanDesc = node->biss_ScanDesc;
 
-	/*
-	 * Free the exprcontext ... now dead code, see ExecFreeExprContext
-	 */
-#ifdef NOT_USED
-	if (node->biss_RuntimeContext)
-		FreeExprContext(node->biss_RuntimeContext, true);
-#endif
-
 	/*
 	 * close the index relation (no-op if we didn't open it)
 	 */
@@ -263,6 +255,8 @@ ExecInitBitmapIndexScan(BitmapIndexScan *node, EState *estate, int eflags)
 	/* Open the index relation. */
 	lockmode = exec_rt_fetch(node->scan.scanrelid, estate)->rellockmode;
 	indexstate->biss_RelationDesc = index_open(node->indexid, lockmode);
+	if (!ExecPlanStillValid(estate))
+		return indexstate;
 
 	/*
 	 * Initialize index-specific scan state
diff --git a/src/backend/executor/nodeBitmapOr.c b/src/backend/executor/nodeBitmapOr.c
index 0bf8af9652..e0e9228e35 100644
--- a/src/backend/executor/nodeBitmapOr.c
+++ b/src/backend/executor/nodeBitmapOr.c
@@ -79,7 +79,6 @@ ExecInitBitmapOr(BitmapOr *node, EState *estate, int eflags)
 	bitmaporstate->ps.state = estate;
 	bitmaporstate->ps.ExecProcNode = ExecBitmapOr;
 	bitmaporstate->bitmapplans = bitmapplanstates;
-	bitmaporstate->nplans = nplans;
 
 	/*
 	 * call ExecInitNode on each of the plans to be executed and save the
@@ -89,8 +88,10 @@ ExecInitBitmapOr(BitmapOr *node, EState *estate, int eflags)
 	foreach(l, node->bitmapplans)
 	{
 		initNode = (Plan *) lfirst(l);
-		bitmapplanstates[i] = ExecInitNode(initNode, estate, eflags);
-		i++;
+		bitmapplanstates[i++] = ExecInitNode(initNode, estate, eflags);
+		if (!ExecPlanStillValid(estate))
+			return bitmaporstate;
+		bitmaporstate->nplans = i;
 	}
 
 	/*
diff --git a/src/backend/executor/nodeCtescan.c b/src/backend/executor/nodeCtescan.c
index cc4c4243e2..a0c0c4be33 100644
--- a/src/backend/executor/nodeCtescan.c
+++ b/src/backend/executor/nodeCtescan.c
@@ -287,18 +287,6 @@ ExecInitCteScan(CteScan *node, EState *estate, int eflags)
 void
 ExecEndCteScan(CteScanState *node)
 {
-	/*
-	 * Free exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	/*
 	 * If I am the leader, free the tuplestore.
 	 */
diff --git a/src/backend/executor/nodeCustom.c b/src/backend/executor/nodeCustom.c
index bd42c65b29..38061c30b9 100644
--- a/src/backend/executor/nodeCustom.c
+++ b/src/backend/executor/nodeCustom.c
@@ -61,6 +61,8 @@ ExecInitCustomScan(CustomScan *cscan, EState *estate, int eflags)
 	if (scanrelid > 0)
 	{
 		scan_rel = ExecOpenScanRelation(estate, scanrelid, eflags);
+		if (!ExecPlanStillValid(estate))
+			return NULL;
 		css->ss.ss_currentRelation = scan_rel;
 	}
 
@@ -127,15 +129,11 @@ ExecCustomScan(PlanState *pstate)
 void
 ExecEndCustomScan(CustomScanState *node)
 {
-	Assert(node->methods->EndCustomScan != NULL);
-	node->methods->EndCustomScan(node);
-
-	/* Free the exprcontext */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/* Clean out the tuple table */
-	ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
+	if (node->methods)
+	{
+		Assert(node->methods->EndCustomScan != NULL);
+		node->methods->EndCustomScan(node);
+	}
 }
 
 void
diff --git a/src/backend/executor/nodeForeignscan.c b/src/backend/executor/nodeForeignscan.c
index c2139acca0..a3705082a9 100644
--- a/src/backend/executor/nodeForeignscan.c
+++ b/src/backend/executor/nodeForeignscan.c
@@ -173,6 +173,8 @@ ExecInitForeignScan(ForeignScan *node, EState *estate, int eflags)
 	if (scanrelid > 0)
 	{
 		currentRelation = ExecOpenScanRelation(estate, scanrelid, eflags);
+		if (!ExecPlanStillValid(estate))
+			return NULL;
 		scanstate->ss.ss_currentRelation = currentRelation;
 		fdwroutine = GetFdwRoutineForRelation(currentRelation, true);
 	}
@@ -264,6 +266,8 @@ ExecInitForeignScan(ForeignScan *node, EState *estate, int eflags)
 	if (outerPlan(node))
 		outerPlanState(scanstate) =
 			ExecInitNode(outerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return scanstate;
 
 	/*
 	 * Tell the FDW to initialize the scan.
@@ -312,14 +316,6 @@ ExecEndForeignScan(ForeignScanState *node)
 	/* Shut down any outer plan. */
 	if (outerPlanState(node))
 		ExecEndNode(outerPlanState(node));
-
-	/* Free the exprcontext */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/* clean out the tuple table */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
 }
 
 /* ----------------------------------------------------------------
diff --git a/src/backend/executor/nodeFunctionscan.c b/src/backend/executor/nodeFunctionscan.c
index dd06ef8aee..a49c1a2c85 100644
--- a/src/backend/executor/nodeFunctionscan.c
+++ b/src/backend/executor/nodeFunctionscan.c
@@ -523,18 +523,6 @@ ExecEndFunctionScan(FunctionScanState *node)
 {
 	int			i;
 
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	/*
 	 * Release slots and tuplestore resources
 	 */
diff --git a/src/backend/executor/nodeGather.c b/src/backend/executor/nodeGather.c
index 307fc10eea..6b26e03f74 100644
--- a/src/backend/executor/nodeGather.c
+++ b/src/backend/executor/nodeGather.c
@@ -89,6 +89,9 @@ ExecInitGather(Gather *node, EState *estate, int eflags)
 	 */
 	outerNode = outerPlan(node);
 	outerPlanState(gatherstate) = ExecInitNode(outerNode, estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return gatherstate;
+
 	tupDesc = ExecGetResultType(outerPlanState(gatherstate));
 
 	/*
@@ -250,9 +253,6 @@ ExecEndGather(GatherState *node)
 {
 	ExecEndNode(outerPlanState(node));	/* let children clean up first */
 	ExecShutdownGather(node);
-	ExecFreeExprContext(&node->ps);
-	if (node->ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ps.ps_ResultTupleSlot);
 }
 
 /*
diff --git a/src/backend/executor/nodeGatherMerge.c b/src/backend/executor/nodeGatherMerge.c
index 9d5e1a46e9..84412f94bb 100644
--- a/src/backend/executor/nodeGatherMerge.c
+++ b/src/backend/executor/nodeGatherMerge.c
@@ -108,6 +108,8 @@ ExecInitGatherMerge(GatherMerge *node, EState *estate, int eflags)
 	 */
 	outerNode = outerPlan(node);
 	outerPlanState(gm_state) = ExecInitNode(outerNode, estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return gm_state;
 
 	/*
 	 * Leader may access ExecProcNode result directly (if
@@ -290,9 +292,6 @@ ExecEndGatherMerge(GatherMergeState *node)
 {
 	ExecEndNode(outerPlanState(node));	/* let children clean up first */
 	ExecShutdownGatherMerge(node);
-	ExecFreeExprContext(&node->ps);
-	if (node->ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ps.ps_ResultTupleSlot);
 }
 
 /* ----------------------------------------------------------------
diff --git a/src/backend/executor/nodeGroup.c b/src/backend/executor/nodeGroup.c
index 25a1618952..b6068887f6 100644
--- a/src/backend/executor/nodeGroup.c
+++ b/src/backend/executor/nodeGroup.c
@@ -185,6 +185,8 @@ ExecInitGroup(Group *node, EState *estate, int eflags)
 	 * initialize child nodes
 	 */
 	outerPlanState(grpstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return grpstate;
 
 	/*
 	 * Initialize scan slot and type.
@@ -228,11 +230,6 @@ ExecEndGroup(GroupState *node)
 {
 	PlanState  *outerPlan;
 
-	ExecFreeExprContext(&node->ss.ps);
-
-	/* clean up tuple table */
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	outerPlan = outerPlanState(node);
 	ExecEndNode(outerPlan);
 }
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 8b5c35b82b..030bf0ed43 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -386,6 +386,8 @@ ExecInitHash(Hash *node, EState *estate, int eflags)
 	 * initialize child nodes
 	 */
 	outerPlanState(hashstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return hashstate;
 
 	/*
 	 * initialize our result slot and type. No need to build projection
@@ -415,11 +417,6 @@ ExecEndHash(HashState *node)
 {
 	PlanState  *outerPlan;
 
-	/*
-	 * free exprcontext
-	 */
-	ExecFreeExprContext(&node->ps);
-
 	/*
 	 * shut down the subplan
 	 */
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 980746128b..49a6ba4276 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -752,8 +752,12 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	hashNode = (Hash *) innerPlan(node);
 
 	outerPlanState(hjstate) = ExecInitNode(outerNode, estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return hjstate;
 	outerDesc = ExecGetResultType(outerPlanState(hjstate));
 	innerPlanState(hjstate) = ExecInitNode((Plan *) hashNode, estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return hjstate;
 	innerDesc = ExecGetResultType(innerPlanState(hjstate));
 
 	/*
@@ -867,18 +871,6 @@ ExecEndHashJoin(HashJoinState *node)
 		node->hj_HashTable = NULL;
 	}
 
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->js.ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	ExecClearTuple(node->js.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->hj_OuterTupleSlot);
-	ExecClearTuple(node->hj_HashTupleSlot);
-
 	/*
 	 * clean up subtrees
 	 */
diff --git a/src/backend/executor/nodeIncrementalSort.c b/src/backend/executor/nodeIncrementalSort.c
index 7683e3341c..6caa1aa306 100644
--- a/src/backend/executor/nodeIncrementalSort.c
+++ b/src/backend/executor/nodeIncrementalSort.c
@@ -1041,6 +1041,8 @@ ExecInitIncrementalSort(IncrementalSort *node, EState *estate, int eflags)
 	 * nodes may be able to do something more useful.
 	 */
 	outerPlanState(incrsortstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return incrsortstate;
 
 	/*
 	 * Initialize scan slot and type.
@@ -1079,14 +1081,6 @@ ExecEndIncrementalSort(IncrementalSortState *node)
 {
 	SO_printf("ExecEndIncrementalSort: shutting down sort node\n");
 
-	/* clean out the scan tuple */
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-	/* must drop pointer to sort result tuple */
-	ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	/* must drop standalone tuple slots from outer node */
-	ExecDropSingleTupleTableSlot(node->group_pivot);
-	ExecDropSingleTupleTableSlot(node->transfer_tuple);
-
 	/*
 	 * Release tuplesort resources.
 	 */
diff --git a/src/backend/executor/nodeIndexonlyscan.c b/src/backend/executor/nodeIndexonlyscan.c
index 0b43a9b969..ea7fd89c0c 100644
--- a/src/backend/executor/nodeIndexonlyscan.c
+++ b/src/backend/executor/nodeIndexonlyscan.c
@@ -380,22 +380,6 @@ ExecEndIndexOnlyScan(IndexOnlyScanState *node)
 		node->ioss_VMBuffer = InvalidBuffer;
 	}
 
-	/*
-	 * Free the exprcontext(s) ... now dead code, see ExecFreeExprContext
-	 */
-#ifdef NOT_USED
-	ExecFreeExprContext(&node->ss.ps);
-	if (node->ioss_RuntimeContext)
-		FreeExprContext(node->ioss_RuntimeContext, true);
-#endif
-
-	/*
-	 * clear out tuple table slots
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	/*
 	 * close the index relation (no-op if we didn't open it)
 	 */
@@ -512,6 +496,8 @@ ExecInitIndexOnlyScan(IndexOnlyScan *node, EState *estate, int eflags)
 	 * open the scan relation
 	 */
 	currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
+	if (!ExecPlanStillValid(estate))
+		return NULL;
 
 	indexstate->ss.ss_currentRelation = currentRelation;
 	indexstate->ss.ss_currentScanDesc = NULL;	/* no heap scan here */
@@ -565,6 +551,8 @@ ExecInitIndexOnlyScan(IndexOnlyScan *node, EState *estate, int eflags)
 	/* Open the index relation. */
 	lockmode = exec_rt_fetch(node->scan.scanrelid, estate)->rellockmode;
 	indexstate->ioss_RelationDesc = index_open(node->indexid, lockmode);
+	if (!ExecPlanStillValid(estate))
+		return NULL;
 
 	/*
 	 * Initialize index-specific scan state
diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c
index 4540c7781d..906358011a 100644
--- a/src/backend/executor/nodeIndexscan.c
+++ b/src/backend/executor/nodeIndexscan.c
@@ -794,22 +794,6 @@ ExecEndIndexScan(IndexScanState *node)
 	indexRelationDesc = node->iss_RelationDesc;
 	indexScanDesc = node->iss_ScanDesc;
 
-	/*
-	 * Free the exprcontext(s) ... now dead code, see ExecFreeExprContext
-	 */
-#ifdef NOT_USED
-	ExecFreeExprContext(&node->ss.ps);
-	if (node->iss_RuntimeContext)
-		FreeExprContext(node->iss_RuntimeContext, true);
-#endif
-
-	/*
-	 * clear out tuple table slots
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	/*
 	 * close the index relation (no-op if we didn't open it)
 	 */
@@ -925,6 +909,8 @@ ExecInitIndexScan(IndexScan *node, EState *estate, int eflags)
 	 * open the scan relation
 	 */
 	currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
+	if (!ExecPlanStillValid(estate))
+		return NULL;
 
 	indexstate->ss.ss_currentRelation = currentRelation;
 	indexstate->ss.ss_currentScanDesc = NULL;	/* no heap scan here */
@@ -970,6 +956,8 @@ ExecInitIndexScan(IndexScan *node, EState *estate, int eflags)
 	/* Open the index relation. */
 	lockmode = exec_rt_fetch(node->scan.scanrelid, estate)->rellockmode;
 	indexstate->iss_RelationDesc = index_open(node->indexid, lockmode);
+	if (!ExecPlanStillValid(estate))
+		return NULL;
 
 	/*
 	 * Initialize index-specific scan state
diff --git a/src/backend/executor/nodeLimit.c b/src/backend/executor/nodeLimit.c
index 425fbfc405..6760de0f25 100644
--- a/src/backend/executor/nodeLimit.c
+++ b/src/backend/executor/nodeLimit.c
@@ -476,6 +476,8 @@ ExecInitLimit(Limit *node, EState *estate, int eflags)
 	 */
 	outerPlan = outerPlan(node);
 	outerPlanState(limitstate) = ExecInitNode(outerPlan, estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return limitstate;
 
 	/*
 	 * initialize child expressions
@@ -534,7 +536,6 @@ ExecInitLimit(Limit *node, EState *estate, int eflags)
 void
 ExecEndLimit(LimitState *node)
 {
-	ExecFreeExprContext(&node->ps);
 	ExecEndNode(outerPlanState(node));
 }
 
diff --git a/src/backend/executor/nodeLockRows.c b/src/backend/executor/nodeLockRows.c
index e459971d32..2599332f01 100644
--- a/src/backend/executor/nodeLockRows.c
+++ b/src/backend/executor/nodeLockRows.c
@@ -322,6 +322,8 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
 	 * then initialize outer plan
 	 */
 	outerPlanState(lrstate) = ExecInitNode(outerPlan, estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return lrstate;
 
 	/* node returns unmodified slots from the outer plan */
 	lrstate->ps.resultopsset = true;
diff --git a/src/backend/executor/nodeMaterial.c b/src/backend/executor/nodeMaterial.c
index 09632678b0..b974ebdc8a 100644
--- a/src/backend/executor/nodeMaterial.c
+++ b/src/backend/executor/nodeMaterial.c
@@ -214,6 +214,8 @@ ExecInitMaterial(Material *node, EState *estate, int eflags)
 
 	outerPlan = outerPlan(node);
 	outerPlanState(matstate) = ExecInitNode(outerPlan, estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return matstate;
 
 	/*
 	 * Initialize result type and slot. No need to initialize projection info
@@ -239,11 +241,6 @@ ExecInitMaterial(Material *node, EState *estate, int eflags)
 void
 ExecEndMaterial(MaterialState *node)
 {
-	/*
-	 * clean out the tuple table
-	 */
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	/*
 	 * Release tuplestore resources
 	 */
diff --git a/src/backend/executor/nodeMemoize.c b/src/backend/executor/nodeMemoize.c
index 4f04269e26..d0cdbe1fd7 100644
--- a/src/backend/executor/nodeMemoize.c
+++ b/src/backend/executor/nodeMemoize.c
@@ -938,6 +938,8 @@ ExecInitMemoize(Memoize *node, EState *estate, int eflags)
 
 	outerNode = outerPlan(node);
 	outerPlanState(mstate) = ExecInitNode(outerNode, estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return mstate;
 
 	/*
 	 * Initialize return slot and type. No need to initialize projection info
@@ -1043,6 +1045,7 @@ ExecEndMemoize(MemoizeState *node)
 {
 #ifdef USE_ASSERT_CHECKING
 	/* Validate the memory accounting code is correct in assert builds. */
+	if (node->hashtable)
 	{
 		int			count;
 		uint64		mem = 0;
@@ -1091,15 +1094,6 @@ ExecEndMemoize(MemoizeState *node)
 	/* Remove the cache context */
 	MemoryContextDelete(node->tableContext);
 
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-	/* must drop pointer to cache result tuple */
-	ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-
-	/*
-	 * free exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
 	/*
 	 * shut down the subplan
 	 */
diff --git a/src/backend/executor/nodeMergeAppend.c b/src/backend/executor/nodeMergeAppend.c
index 21b5726e6e..255b05aad3 100644
--- a/src/backend/executor/nodeMergeAppend.c
+++ b/src/backend/executor/nodeMergeAppend.c
@@ -95,6 +95,8 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 											  list_length(node->mergeplans),
 											  node->part_prune_info,
 											  &validsubplans);
+		if (!ExecPlanStillValid(estate))
+			return NULL;
 		mergestate->ms_prune_state = prunestate;
 		nplans = bms_num_members(validsubplans);
 
@@ -120,7 +122,7 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		mergestate->ms_prune_state = NULL;
 	}
 
-	mergeplanstates = (PlanState **) palloc(nplans * sizeof(PlanState *));
+	mergeplanstates = (PlanState **) palloc0(nplans * sizeof(PlanState *));
 	mergestate->mergeplans = mergeplanstates;
 	mergestate->ms_nplans = nplans;
 
@@ -151,6 +153,8 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 		Plan	   *initNode = (Plan *) list_nth(node->mergeplans, i);
 
 		mergeplanstates[j++] = ExecInitNode(initNode, estate, eflags);
+		if (!ExecPlanStillValid(estate))
+			return mergestate;
 	}
 
 	mergestate->ps.ps_ProjInfo = NULL;
diff --git a/src/backend/executor/nodeMergejoin.c b/src/backend/executor/nodeMergejoin.c
index 00f96d045e..e7f4512419 100644
--- a/src/backend/executor/nodeMergejoin.c
+++ b/src/backend/executor/nodeMergejoin.c
@@ -1490,11 +1490,15 @@ ExecInitMergeJoin(MergeJoin *node, EState *estate, int eflags)
 	mergestate->mj_SkipMarkRestore = node->skip_mark_restore;
 
 	outerPlanState(mergestate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return mergestate;
 	outerDesc = ExecGetResultType(outerPlanState(mergestate));
 	innerPlanState(mergestate) = ExecInitNode(innerPlan(node), estate,
 											  mergestate->mj_SkipMarkRestore ?
 											  eflags :
 											  (eflags | EXEC_FLAG_MARK));
+	if (!ExecPlanStillValid(estate))
+		return mergestate;
 	innerDesc = ExecGetResultType(innerPlanState(mergestate));
 
 	/*
@@ -1642,18 +1646,6 @@ ExecEndMergeJoin(MergeJoinState *node)
 {
 	MJ1_printf("ExecEndMergeJoin: %s\n",
 			   "ending node processing");
-
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->js.ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	ExecClearTuple(node->js.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->mj_MarkedTupleSlot);
-
 	/*
 	 * shut down the subplans
 	 */
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 5005d8c0d1..c28d5058e9 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -3985,6 +3985,9 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 							   linitial_int(node->resultRelations));
 	}
 
+	if (!ExecPlanStillValid(estate))
+		return NULL;
+
 	/* set up epqstate with dummy subplan data for the moment */
 	EvalPlanQualInit(&mtstate->mt_epqstate, estate, NULL, NIL,
 					 node->epqParam, node->resultRelations);
@@ -4012,6 +4015,8 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 		if (resultRelInfo != mtstate->rootResultRelInfo)
 		{
 			ExecInitResultRelation(estate, resultRelInfo, resultRelation);
+			if (!ExecPlanStillValid(estate))
+				return NULL;
 
 			/*
 			 * For child result relations, store the root result relation
@@ -4039,6 +4044,8 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 	 * Now we may initialize the subplan.
 	 */
 	outerPlanState(mtstate) = ExecInitNode(subplan, estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return mtstate;
 
 	/*
 	 * Do additional per-result-relation initialization.
@@ -4446,17 +4453,6 @@ ExecEndModifyTable(ModifyTableState *node)
 			ExecDropSingleTupleTableSlot(node->mt_root_tuple_slot);
 	}
 
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	if (node->ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ps.ps_ResultTupleSlot);
-
 	/*
 	 * Terminate EPQ execution if active
 	 */
diff --git a/src/backend/executor/nodeNamedtuplestorescan.c b/src/backend/executor/nodeNamedtuplestorescan.c
index 46832ad82f..e142ef593b 100644
--- a/src/backend/executor/nodeNamedtuplestorescan.c
+++ b/src/backend/executor/nodeNamedtuplestorescan.c
@@ -164,17 +164,6 @@ ExecInitNamedTuplestoreScan(NamedTuplestoreScan *node, EState *estate, int eflag
 void
 ExecEndNamedTuplestoreScan(NamedTuplestoreScanState *node)
 {
-	/*
-	 * Free exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
 }
 
 /* ----------------------------------------------------------------
diff --git a/src/backend/executor/nodeNestloop.c b/src/backend/executor/nodeNestloop.c
index b3d52e69ec..0158a3e592 100644
--- a/src/backend/executor/nodeNestloop.c
+++ b/src/backend/executor/nodeNestloop.c
@@ -295,11 +295,15 @@ ExecInitNestLoop(NestLoop *node, EState *estate, int eflags)
 	 * values.
 	 */
 	outerPlanState(nlstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return nlstate;
 	if (node->nestParams == NIL)
 		eflags |= EXEC_FLAG_REWIND;
 	else
 		eflags &= ~EXEC_FLAG_REWIND;
 	innerPlanState(nlstate) = ExecInitNode(innerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return nlstate;
 
 	/*
 	 * Initialize result slot, type and projection.
@@ -363,17 +367,6 @@ ExecEndNestLoop(NestLoopState *node)
 {
 	NL1_printf("ExecEndNestLoop: %s\n",
 			   "ending node processing");
-
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->js.ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	ExecClearTuple(node->js.ps.ps_ResultTupleSlot);
-
 	/*
 	 * close down subplans
 	 */
diff --git a/src/backend/executor/nodeProjectSet.c b/src/backend/executor/nodeProjectSet.c
index f6ff3dc44c..1b4774d4f7 100644
--- a/src/backend/executor/nodeProjectSet.c
+++ b/src/backend/executor/nodeProjectSet.c
@@ -247,6 +247,8 @@ ExecInitProjectSet(ProjectSet *node, EState *estate, int eflags)
 	 * initialize child nodes
 	 */
 	outerPlanState(state) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return state;
 
 	/*
 	 * we don't use inner plan
@@ -320,16 +322,6 @@ ExecInitProjectSet(ProjectSet *node, EState *estate, int eflags)
 void
 ExecEndProjectSet(ProjectSetState *node)
 {
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	ExecClearTuple(node->ps.ps_ResultTupleSlot);
-
 	/*
 	 * shut down subplans
 	 */
diff --git a/src/backend/executor/nodeRecursiveunion.c b/src/backend/executor/nodeRecursiveunion.c
index e781003934..ca4f78685d 100644
--- a/src/backend/executor/nodeRecursiveunion.c
+++ b/src/backend/executor/nodeRecursiveunion.c
@@ -244,7 +244,11 @@ ExecInitRecursiveUnion(RecursiveUnion *node, EState *estate, int eflags)
 	 * initialize child nodes
 	 */
 	outerPlanState(rustate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return rustate;
 	innerPlanState(rustate) = ExecInitNode(innerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return rustate;
 
 	/*
 	 * If hashing, precompute fmgr lookup data for inner loop, and create the
@@ -272,8 +276,10 @@ void
 ExecEndRecursiveUnion(RecursiveUnionState *node)
 {
 	/* Release tuplestores */
-	tuplestore_end(node->working_table);
-	tuplestore_end(node->intermediate_table);
+	if (node->working_table)
+		tuplestore_end(node->working_table);
+	if (node->intermediate_table)
+		tuplestore_end(node->intermediate_table);
 
 	/* free subsidiary stuff including hashtable */
 	if (node->tempContext)
diff --git a/src/backend/executor/nodeResult.c b/src/backend/executor/nodeResult.c
index 4219712d30..d4ea101cbe 100644
--- a/src/backend/executor/nodeResult.c
+++ b/src/backend/executor/nodeResult.c
@@ -208,6 +208,8 @@ ExecInitResult(Result *node, EState *estate, int eflags)
 	 * initialize child nodes
 	 */
 	outerPlanState(resstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return resstate;
 
 	/*
 	 * we don't use inner plan
@@ -240,16 +242,6 @@ ExecInitResult(Result *node, EState *estate, int eflags)
 void
 ExecEndResult(ResultState *node)
 {
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	ExecClearTuple(node->ps.ps_ResultTupleSlot);
-
 	/*
 	 * shut down subplans
 	 */
diff --git a/src/backend/executor/nodeSamplescan.c b/src/backend/executor/nodeSamplescan.c
index d7e22b1dbb..02a7db96e1 100644
--- a/src/backend/executor/nodeSamplescan.c
+++ b/src/backend/executor/nodeSamplescan.c
@@ -125,6 +125,8 @@ ExecInitSampleScan(SampleScan *node, EState *estate, int eflags)
 		ExecOpenScanRelation(estate,
 							 node->scan.scanrelid,
 							 eflags);
+	if (!ExecPlanStillValid(estate))
+		return NULL;
 
 	/* we won't set up the HeapScanDesc till later */
 	scanstate->ss.ss_currentScanDesc = NULL;
@@ -185,21 +187,9 @@ ExecEndSampleScan(SampleScanState *node)
 	/*
 	 * Tell sampling function that we finished the scan.
 	 */
-	if (node->tsmroutine->EndSampleScan)
+	if (node->tsmroutine && node->tsmroutine->EndSampleScan)
 		node->tsmroutine->EndSampleScan(node);
 
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	/*
 	 * close heap scan
 	 */
diff --git a/src/backend/executor/nodeSeqscan.c b/src/backend/executor/nodeSeqscan.c
index 4da0f28f7b..48e20aa735 100644
--- a/src/backend/executor/nodeSeqscan.c
+++ b/src/backend/executor/nodeSeqscan.c
@@ -153,6 +153,8 @@ ExecInitSeqScan(SeqScan *node, EState *estate, int eflags)
 		ExecOpenScanRelation(estate,
 							 node->scan.scanrelid,
 							 eflags);
+	if (!ExecPlanStillValid(estate))
+		return NULL;
 
 	/* and create slot with the appropriate rowtype */
 	ExecInitScanTupleSlot(estate, &scanstate->ss,
@@ -190,18 +192,6 @@ ExecEndSeqScan(SeqScanState *node)
 	 */
 	scanDesc = node->ss.ss_currentScanDesc;
 
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	/*
 	 * close heap scan
 	 */
diff --git a/src/backend/executor/nodeSetOp.c b/src/backend/executor/nodeSetOp.c
index 4bc2406b89..7a3a142204 100644
--- a/src/backend/executor/nodeSetOp.c
+++ b/src/backend/executor/nodeSetOp.c
@@ -528,6 +528,8 @@ ExecInitSetOp(SetOp *node, EState *estate, int eflags)
 	if (node->strategy == SETOP_HASHED)
 		eflags &= ~EXEC_FLAG_REWIND;
 	outerPlanState(setopstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return setopstate;
 	outerDesc = ExecGetResultType(outerPlanState(setopstate));
 
 	/*
@@ -582,13 +584,9 @@ ExecInitSetOp(SetOp *node, EState *estate, int eflags)
 void
 ExecEndSetOp(SetOpState *node)
 {
-	/* clean up tuple table */
-	ExecClearTuple(node->ps.ps_ResultTupleSlot);
-
 	/* free subsidiary stuff including hashtable */
 	if (node->tableContext)
 		MemoryContextDelete(node->tableContext);
-	ExecFreeExprContext(&node->ps);
 
 	ExecEndNode(outerPlanState(node));
 }
diff --git a/src/backend/executor/nodeSort.c b/src/backend/executor/nodeSort.c
index c6c72c6e67..3ebbc46604 100644
--- a/src/backend/executor/nodeSort.c
+++ b/src/backend/executor/nodeSort.c
@@ -263,6 +263,8 @@ ExecInitSort(Sort *node, EState *estate, int eflags)
 	eflags &= ~(EXEC_FLAG_REWIND | EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK);
 
 	outerPlanState(sortstate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return sortstate;
 
 	/*
 	 * Initialize scan slot and type.
@@ -303,13 +305,6 @@ ExecEndSort(SortState *node)
 	SO1_printf("ExecEndSort: %s\n",
 			   "shutting down sort node");
 
-	/*
-	 * clean out the tuple table
-	 */
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-	/* must drop pointer to sort result tuple */
-	ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-
 	/*
 	 * Release tuplesort resources
 	 */
diff --git a/src/backend/executor/nodeSubqueryscan.c b/src/backend/executor/nodeSubqueryscan.c
index 42471bfc04..3c5c7c2ebb 100644
--- a/src/backend/executor/nodeSubqueryscan.c
+++ b/src/backend/executor/nodeSubqueryscan.c
@@ -124,6 +124,8 @@ ExecInitSubqueryScan(SubqueryScan *node, EState *estate, int eflags)
 	 * initialize subquery
 	 */
 	subquerystate->subplan = ExecInitNode(node->subplan, estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return subquerystate;
 
 	/*
 	 * Initialize scan slot and type (needed by ExecAssignScanProjectionInfo)
@@ -167,18 +169,6 @@ ExecInitSubqueryScan(SubqueryScan *node, EState *estate, int eflags)
 void
 ExecEndSubqueryScan(SubqueryScanState *node)
 {
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clean out the upper tuple table
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	/*
 	 * close down subquery
 	 */
diff --git a/src/backend/executor/nodeTableFuncscan.c b/src/backend/executor/nodeTableFuncscan.c
index 791cbd2372..a60dcd4943 100644
--- a/src/backend/executor/nodeTableFuncscan.c
+++ b/src/backend/executor/nodeTableFuncscan.c
@@ -213,18 +213,6 @@ ExecInitTableFuncScan(TableFuncScan *node, EState *estate, int eflags)
 void
 ExecEndTableFuncScan(TableFuncScanState *node)
 {
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	/*
 	 * Release tuplestore resources
 	 */
diff --git a/src/backend/executor/nodeTidrangescan.c b/src/backend/executor/nodeTidrangescan.c
index 2124c55ef5..d337f3d54a 100644
--- a/src/backend/executor/nodeTidrangescan.c
+++ b/src/backend/executor/nodeTidrangescan.c
@@ -331,18 +331,6 @@ ExecEndTidRangeScan(TidRangeScanState *node)
 
 	if (scan != NULL)
 		table_endscan(scan);
-
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clear out tuple table slots
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
 }
 
 /* ----------------------------------------------------------------
@@ -386,6 +374,8 @@ ExecInitTidRangeScan(TidRangeScan *node, EState *estate, int eflags)
 	 * open the scan relation
 	 */
 	currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
+	if (!ExecPlanStillValid(estate))
+		return NULL;
 
 	tidrangestate->ss.ss_currentRelation = currentRelation;
 	tidrangestate->ss.ss_currentScanDesc = NULL;	/* no table scan here */
diff --git a/src/backend/executor/nodeTidscan.c b/src/backend/executor/nodeTidscan.c
index 862bd0330b..9637f354b2 100644
--- a/src/backend/executor/nodeTidscan.c
+++ b/src/backend/executor/nodeTidscan.c
@@ -472,18 +472,6 @@ ExecEndTidScan(TidScanState *node)
 {
 	if (node->ss.ss_currentScanDesc)
 		table_endscan(node->ss.ss_currentScanDesc);
-
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clear out tuple table slots
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
 }
 
 /* ----------------------------------------------------------------
@@ -529,6 +517,8 @@ ExecInitTidScan(TidScan *node, EState *estate, int eflags)
 	 * open the scan relation
 	 */
 	currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
+	if (!ExecPlanStillValid(estate))
+		return NULL;
 
 	tidstate->ss.ss_currentRelation = currentRelation;
 	tidstate->ss.ss_currentScanDesc = NULL; /* no heap scan here */
diff --git a/src/backend/executor/nodeUnique.c b/src/backend/executor/nodeUnique.c
index 45035d74fa..28630e380e 100644
--- a/src/backend/executor/nodeUnique.c
+++ b/src/backend/executor/nodeUnique.c
@@ -136,6 +136,8 @@ ExecInitUnique(Unique *node, EState *estate, int eflags)
 	 * then initialize outer plan
 	 */
 	outerPlanState(uniquestate) = ExecInitNode(outerPlan(node), estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return uniquestate;
 
 	/*
 	 * Initialize result slot and type. Unique nodes do no projections, so
@@ -168,11 +170,6 @@ ExecInitUnique(Unique *node, EState *estate, int eflags)
 void
 ExecEndUnique(UniqueState *node)
 {
-	/* clean up tuple table */
-	ExecClearTuple(node->ps.ps_ResultTupleSlot);
-
-	ExecFreeExprContext(&node->ps);
-
 	ExecEndNode(outerPlanState(node));
 }
 
diff --git a/src/backend/executor/nodeValuesscan.c b/src/backend/executor/nodeValuesscan.c
index 32ace63017..3f86783ad7 100644
--- a/src/backend/executor/nodeValuesscan.c
+++ b/src/backend/executor/nodeValuesscan.c
@@ -328,19 +328,6 @@ ExecInitValuesScan(ValuesScan *node, EState *estate, int eflags)
 void
 ExecEndValuesScan(ValuesScanState *node)
 {
-	/*
-	 * Free both exprcontexts
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-	node->ss.ps.ps_ExprContext = node->rowcontext;
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
 }
 
 /* ----------------------------------------------------------------
diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index 310ac23e3a..a4153be495 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -2458,6 +2458,8 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 	 */
 	outerPlan = outerPlan(node);
 	outerPlanState(winstate) = ExecInitNode(outerPlan, estate, eflags);
+	if (!ExecPlanStillValid(estate))
+		return winstate;
 
 	/*
 	 * initialize source tuple type (which is also the tuple type that we'll
@@ -2691,17 +2693,6 @@ ExecEndWindowAgg(WindowAggState *node)
 	ExecClearTuple(node->agg_row_slot);
 	ExecClearTuple(node->temp_slot_1);
 	ExecClearTuple(node->temp_slot_2);
-	if (node->framehead_slot)
-		ExecClearTuple(node->framehead_slot);
-	if (node->frametail_slot)
-		ExecClearTuple(node->frametail_slot);
-
-	/*
-	 * Free both the expr contexts.
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-	node->ss.ps.ps_ExprContext = node->tmpcontext;
-	ExecFreeExprContext(&node->ss.ps);
 
 	for (i = 0; i < node->numaggs; i++)
 	{
diff --git a/src/backend/executor/nodeWorktablescan.c b/src/backend/executor/nodeWorktablescan.c
index 0c13448236..cc63ddfeca 100644
--- a/src/backend/executor/nodeWorktablescan.c
+++ b/src/backend/executor/nodeWorktablescan.c
@@ -190,17 +190,6 @@ ExecInitWorkTableScan(WorkTableScan *node, EState *estate, int eflags)
 void
 ExecEndWorkTableScan(WorkTableScanState *node)
 {
-	/*
-	 * Free exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
 }
 
 /* ----------------------------------------------------------------
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index c677e490d7..8ec636cab8 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -19,6 +19,7 @@
 #include "nodes/lockoptions.h"
 #include "nodes/parsenodes.h"
 #include "utils/memutils.h"
+#include "utils/plancache.h"
 
 
 /*
@@ -256,6 +257,17 @@ extern void ExecEndNode(PlanState *node);
 extern void ExecShutdownNode(PlanState *node);
 extern void ExecSetTupleBound(int64 tuples_needed, PlanState *child_node);
 
+/*
+ * Is the cached plan, if any, still valid at this point?  That is, not
+ * invalidated by the incoming invalidation messages that have been processed
+ * recently.
+ */
+static inline bool
+ExecPlanStillValid(EState *estate)
+{
+	return estate->es_cachedplan == NULL ? true :
+		CachedPlanStillValid(estate->es_cachedplan);
+}
 
 /* ----------------------------------------------------------------
  *		ExecProcNode
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index cb714f4a19..719a728319 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -623,6 +623,8 @@ typedef struct EState
 										 * ExecRowMarks, or NULL if none */
 	List	   *es_rteperminfos;	/* List of RTEPermissionInfo */
 	PlannedStmt *es_plannedstmt;	/* link to top of plan tree */
+	struct CachedPlan  *es_cachedplan;	/* CachedPlan if plannedstmt is from,
+										 * one or NULL if not */
 	const char *es_sourceText;	/* Source text from QueryDesc */
 
 	JunkFilter *es_junkFilter;	/* top-level junk filter, if any */
diff --git a/src/include/utils/plancache.h b/src/include/utils/plancache.h
index 916e59d9fe..c83a67fea3 100644
--- a/src/include/utils/plancache.h
+++ b/src/include/utils/plancache.h
@@ -221,6 +221,20 @@ extern CachedPlan *GetCachedPlan(CachedPlanSource *plansource,
 								 ParamListInfo boundParams,
 								 ResourceOwner owner,
 								 QueryEnvironment *queryEnv);
+
+/*
+ * CachedPlanStillValid
+ *		Returns if a cached generic plan is still valid
+ *
+ * Called by the executor on every relation lock taken when initializing the
+ * plan tree in the CachedPlan.
+ */
+static inline bool
+CachedPlanStillValid(CachedPlan *cplan)
+{
+	return cplan->is_valid;
+}
+
 extern void ReleaseCachedPlan(CachedPlan *plan, ResourceOwner owner);
 
 extern bool CachedPlanAllowsSimpleValidityCheck(CachedPlanSource *plansource,
-- 
2.35.3