diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index e30db12113b4..4cc338e63743 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -606,6 +606,18 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 						(node != NULL &&
 						 node->onConflictAction != ONCONFLICT_NONE));
 
+	if (node != NULL &&
+		(list_length(node->withCheckOptionLists) > 0 ||
+		 list_length(node->returningLists) > 0 ||
+		 node->onConflictAction != ONCONFLICT_NONE ||
+		 node->operation == CMD_MERGE))
+	{
+		part_attmap =
+			build_attrmap_by_name(RelationGetDescr(partrel),
+								  RelationGetDescr(firstResultRel),
+								  false);
+	}
+
 	/*
 	 * Build WITH CHECK OPTION constraints for the partition.  Note that we
 	 * didn't build the withCheckOptionList for partitions within the planner,
@@ -648,10 +660,6 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		/*
 		 * Convert Vars in it to contain this partition's attribute numbers.
 		 */
-		part_attmap =
-			build_attrmap_by_name(RelationGetDescr(partrel),
-								  RelationGetDescr(firstResultRel),
-								  false);
 		wcoList = (List *)
 			map_variable_attnos((Node *) wcoList,
 								firstVarno, 0,
@@ -705,14 +713,6 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		 */
 		returningList = linitial(node->returningLists);
 
-		/*
-		 * Convert Vars in it to contain this partition's attribute numbers.
-		 */
-		if (part_attmap == NULL)
-			part_attmap =
-				build_attrmap_by_name(RelationGetDescr(partrel),
-									  RelationGetDescr(firstResultRel),
-									  false);
 		returningList = (List *)
 			map_variable_attnos((Node *) returningList,
 								firstVarno, 0,
@@ -923,11 +923,7 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				 * target relation (firstVarno).
 				 */
 				onconflset = copyObject(node->onConflictSet);
-				if (part_attmap == NULL)
-					part_attmap =
-						build_attrmap_by_name(RelationGetDescr(partrel),
-											  RelationGetDescr(firstResultRel),
-											  false);
+
 				onconflset = (List *)
 					map_variable_attnos((Node *) onconflset,
 										INNER_VAR, 0,
@@ -1023,12 +1019,6 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		ExprContext *econtext = mtstate->ps.ps_ExprContext;
 		Node	   *joinCondition;
 
-		if (part_attmap == NULL)
-			part_attmap =
-				build_attrmap_by_name(RelationGetDescr(partrel),
-									  RelationGetDescr(firstResultRel),
-									  false);
-
 		if (unlikely(!leaf_part_rri->ri_projectNewInfoValid))
 			ExecInitMergeTupleSlots(mtstate, leaf_part_rri);