diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 493ff82775f..47f21316429 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -195,9 +195,14 @@ standard_ExecutorStart(QueryDesc *queryDesc, int eflags)
 	 */
 	estate->es_param_list_info = queryDesc->params;
 
-	if (queryDesc->plannedstmt->nParamExec > 0)
+	if (queryDesc->plannedstmt->paramExecTypes != NIL)
+	{
+		int			nParamExec;
+
+		nParamExec = list_length(queryDesc->plannedstmt->paramExecTypes);
 		estate->es_param_exec_vals = (ParamExecData *)
-			palloc0(queryDesc->plannedstmt->nParamExec * sizeof(ParamExecData));
+			palloc0(nParamExec * sizeof(ParamExecData));
+	}
 
 	estate->es_sourceText = queryDesc->sourceText;
 
@@ -3032,9 +3037,11 @@ EvalPlanQualBegin(EPQState *epqstate, EState *parentestate)
 		MemSet(estate->es_epqScanDone, 0, rtsize * sizeof(bool));
 
 		/* Recopy current values of parent parameters */
-		if (parentestate->es_plannedstmt->nParamExec > 0)
+		if (parentestate->es_plannedstmt->paramExecTypes != NIL)
 		{
-			int			i = parentestate->es_plannedstmt->nParamExec;
+			int			i;
+
+			i = list_length(parentestate->es_plannedstmt->paramExecTypes);
 
 			while (--i >= 0)
 			{
@@ -3122,10 +3129,11 @@ EvalPlanQualStart(EPQState *epqstate, EState *parentestate, Plan *planTree)
 	 * already set from other parts of the parent's plan tree.
 	 */
 	estate->es_param_list_info = parentestate->es_param_list_info;
-	if (parentestate->es_plannedstmt->nParamExec > 0)
+	if (parentestate->es_plannedstmt->paramExecTypes != NIL)
 	{
-		int			i = parentestate->es_plannedstmt->nParamExec;
+		int			i;
 
+		i = list_length(parentestate->es_plannedstmt->paramExecTypes);
 		estate->es_param_exec_vals = (ParamExecData *)
 			palloc0(i * sizeof(ParamExecData));
 		while (--i >= 0)
diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c
index 1b477baecb8..fd7e7cbf3d3 100644
--- a/src/backend/executor/execParallel.c
+++ b/src/backend/executor/execParallel.c
@@ -195,7 +195,7 @@ ExecSerializePlan(Plan *plan, EState *estate)
 	pstmt->rowMarks = NIL;
 	pstmt->relationOids = NIL;
 	pstmt->invalItems = NIL;	/* workers can't replan anyway... */
-	pstmt->nParamExec = estate->es_plannedstmt->nParamExec;
+	pstmt->paramExecTypes = estate->es_plannedstmt->paramExecTypes;
 	pstmt->utilityStmt = NULL;
 	pstmt->stmt_location = -1;
 	pstmt->stmt_len = -1;
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index cadd253ef17..76e75459b46 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -97,7 +97,7 @@ _copyPlannedStmt(const PlannedStmt *from)
 	COPY_NODE_FIELD(rowMarks);
 	COPY_NODE_FIELD(relationOids);
 	COPY_NODE_FIELD(invalItems);
-	COPY_SCALAR_FIELD(nParamExec);
+	COPY_NODE_FIELD(paramExecTypes);
 	COPY_NODE_FIELD(utilityStmt);
 	COPY_LOCATION_FIELD(stmt_location);
 	COPY_LOCATION_FIELD(stmt_len);
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 291d1eeb46f..dc35df9e4fe 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -282,7 +282,7 @@ _outPlannedStmt(StringInfo str, const PlannedStmt *node)
 	WRITE_NODE_FIELD(rowMarks);
 	WRITE_NODE_FIELD(relationOids);
 	WRITE_NODE_FIELD(invalItems);
-	WRITE_INT_FIELD(nParamExec);
+	WRITE_NODE_FIELD(paramExecTypes);
 	WRITE_NODE_FIELD(utilityStmt);
 	WRITE_LOCATION_FIELD(stmt_location);
 	WRITE_LOCATION_FIELD(stmt_len);
@@ -2181,7 +2181,7 @@ _outPlannerGlobal(StringInfo str, const PlannerGlobal *node)
 	WRITE_NODE_FIELD(rootResultRelations);
 	WRITE_NODE_FIELD(relationOids);
 	WRITE_NODE_FIELD(invalItems);
-	WRITE_INT_FIELD(nParamExec);
+	WRITE_NODE_FIELD(paramExecTypes);
 	WRITE_UINT_FIELD(lastPHId);
 	WRITE_UINT_FIELD(lastRowMarkId);
 	WRITE_INT_FIELD(lastPlanNodeId);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 42c595dc039..593658dd8a8 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1480,7 +1480,7 @@ _readPlannedStmt(void)
 	READ_NODE_FIELD(rowMarks);
 	READ_NODE_FIELD(relationOids);
 	READ_NODE_FIELD(invalItems);
-	READ_INT_FIELD(nParamExec);
+	READ_NODE_FIELD(paramExecTypes);
 	READ_NODE_FIELD(utilityStmt);
 	READ_LOCATION_FIELD(stmt_location);
 	READ_LOCATION_FIELD(stmt_len);
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 9b7a8fd82c4..607f7cd2518 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -243,7 +243,7 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	glob->rootResultRelations = NIL;
 	glob->relationOids = NIL;
 	glob->invalItems = NIL;
-	glob->nParamExec = 0;
+	glob->paramExecTypes = NIL;
 	glob->lastPHId = 0;
 	glob->lastRowMarkId = 0;
 	glob->lastPlanNodeId = 0;
@@ -415,7 +415,7 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	 * set_plan_references' tree traversal, but for now it has to be separate
 	 * because we need to visit subplans before not after main plan.
 	 */
-	if (glob->nParamExec > 0)
+	if (glob->paramExecTypes != NIL)
 	{
 		Assert(list_length(glob->subplans) == list_length(glob->subroots));
 		forboth(lp, glob->subplans, lr, glob->subroots)
@@ -466,7 +466,7 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	result->rowMarks = glob->finalrowmarks;
 	result->relationOids = glob->relationOids;
 	result->invalItems = glob->invalItems;
-	result->nParamExec = glob->nParamExec;
+	result->paramExecTypes = glob->paramExecTypes;
 	/* utilityStmt should be null, but we might as well copy it */
 	result->utilityStmt = parse->utilityStmt;
 	result->stmt_location = parse->stmt_location;
diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index 8f75fa98edc..2e3abeea3d0 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -131,7 +131,9 @@ assign_param_for_var(PlannerInfo *root, Var *var)
 
 	pitem = makeNode(PlannerParamItem);
 	pitem->item = (Node *) var;
-	pitem->paramId = root->glob->nParamExec++;
+	pitem->paramId = list_length(root->glob->paramExecTypes);
+	root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes,
+											 var->vartype);
 
 	root->plan_params = lappend(root->plan_params, pitem);
 
@@ -234,7 +236,9 @@ assign_param_for_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv)
 
 	pitem = makeNode(PlannerParamItem);
 	pitem->item = (Node *) phv;
-	pitem->paramId = root->glob->nParamExec++;
+	pitem->paramId = list_length(root->glob->paramExecTypes);
+	root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes,
+											 exprType((Node *) phv->phexpr));
 
 	root->plan_params = lappend(root->plan_params, pitem);
 
@@ -323,7 +327,9 @@ replace_outer_agg(PlannerInfo *root, Aggref *agg)
 
 	pitem = makeNode(PlannerParamItem);
 	pitem->item = (Node *) agg;
-	pitem->paramId = root->glob->nParamExec++;
+	pitem->paramId = list_length(root->glob->paramExecTypes);
+	root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes,
+											 agg->aggtype);
 
 	root->plan_params = lappend(root->plan_params, pitem);
 
@@ -348,6 +354,7 @@ replace_outer_grouping(PlannerInfo *root, GroupingFunc *grp)
 	Param	   *retval;
 	PlannerParamItem *pitem;
 	Index		levelsup;
+	Oid			ptype;
 
 	Assert(grp->agglevelsup > 0 && grp->agglevelsup < root->query_level);
 
@@ -362,17 +369,20 @@ replace_outer_grouping(PlannerInfo *root, GroupingFunc *grp)
 	grp = copyObject(grp);
 	IncrementVarSublevelsUp((Node *) grp, -((int) grp->agglevelsup), 0);
 	Assert(grp->agglevelsup == 0);
+	ptype = exprType((Node *) grp);
 
 	pitem = makeNode(PlannerParamItem);
 	pitem->item = (Node *) grp;
-	pitem->paramId = root->glob->nParamExec++;
+	pitem->paramId = list_length(root->glob->paramExecTypes);
+	root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes,
+											 ptype);
 
 	root->plan_params = lappend(root->plan_params, pitem);
 
 	retval = makeNode(Param);
 	retval->paramkind = PARAM_EXEC;
 	retval->paramid = pitem->paramId;
-	retval->paramtype = exprType((Node *) grp);
+	retval->paramtype = ptype;
 	retval->paramtypmod = -1;
 	retval->paramcollid = InvalidOid;
 	retval->location = grp->location;
@@ -385,7 +395,8 @@ replace_outer_grouping(PlannerInfo *root, GroupingFunc *grp)
  *
  * This is used to create Params representing subplan outputs.
  * We don't need to build a PlannerParamItem for such a Param, but we do
- * need to record the PARAM_EXEC slot number as being allocated.
+ * need to make sure we record the type in paramExecTypes (otherwise,
+ * there won't be a slot allocated for it).
  */
 static Param *
 generate_new_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod,
@@ -395,7 +406,9 @@ generate_new_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod,
 
 	retval = makeNode(Param);
 	retval->paramkind = PARAM_EXEC;
-	retval->paramid = root->glob->nParamExec++;
+	retval->paramid = list_length(root->glob->paramExecTypes);
+	root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes,
+											 paramtype);
 	retval->paramtype = paramtype;
 	retval->paramtypmod = paramtypmod;
 	retval->paramcollid = paramcollation;
@@ -415,7 +428,11 @@ generate_new_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod,
 int
 SS_assign_special_param(PlannerInfo *root)
 {
-	return root->glob->nParamExec++;
+	int			paramId = list_length(root->glob->paramExecTypes);
+
+	root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes,
+											 InvalidOid);
+	return paramId;
 }
 
 /*
@@ -2098,7 +2115,7 @@ SS_identify_outer_params(PlannerInfo *root)
 	 * If no parameters have been assigned anywhere in the tree, we certainly
 	 * don't need to do anything here.
 	 */
-	if (root->glob->nParamExec == 0)
+	if (root->glob->paramExecTypes == NIL)
 		return;
 
 	/*
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 30cdd3da4c5..66e098f488a 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -1095,7 +1095,7 @@ is_parallel_safe(PlannerInfo *root, Node *node)
 	 * in this expression.  But otherwise we don't need to look.
 	 */
 	if (root->glob->maxParallelHazard == PROPARALLEL_SAFE &&
-		root->glob->nParamExec == 0)
+		root->glob->paramExecTypes == NIL)
 		return true;
 	/* Else use max_parallel_hazard's search logic, but stop on RESTRICTED */
 	context.max_hazard = PROPARALLEL_SAFE;
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index dd74efa9a41..a127682b0e7 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -89,7 +89,7 @@ typedef struct PlannedStmt
 
 	List	   *invalItems;		/* other dependencies, as PlanInvalItems */
 
-	int			nParamExec;		/* number of PARAM_EXEC Params used */
+	List	   *paramExecTypes; /* type OIDs for PARAM_EXEC Params */
 
 	Node	   *utilityStmt;	/* non-null if this is utility stmt */
 
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index 05fc9a3f485..9e68e65cc63 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -114,7 +114,7 @@ typedef struct PlannerGlobal
 
 	List	   *invalItems;		/* other dependencies, as PlanInvalItems */
 
-	int			nParamExec;		/* number of PARAM_EXEC Params used */
+	List	   *paramExecTypes; /* type OIDs for PARAM_EXEC Params */
 
 	Index		lastPHId;		/* highest PlaceHolderVar ID assigned */
 
@@ -2219,8 +2219,8 @@ typedef struct MinMaxAggInfo
  * from subplans (values that are setParam items for those subplans).  These
  * IDs need not be tracked via PlannerParamItems, since we do not need any
  * duplicate-elimination nor later processing of the represented expressions.
- * Instead, we just record the assignment of the slot number by incrementing
- * root->glob->nParamExec.
+ * Instead, we just record the assignment of the slot number by appending to
+ * root->glob->paramExecTypes.
  */
 typedef struct PlannerParamItem
 {