diff --git a/src/backend/distributed/master/master_metadata_utility.c b/src/backend/distributed/master/master_metadata_utility.c
index 9aeb855d2..084ee1555 100644
--- a/src/backend/distributed/master/master_metadata_utility.c
+++ b/src/backend/distributed/master/master_metadata_utility.c
@@ -158,7 +158,6 @@ static uint64
 DistributedTableSize(Oid relationId, char *sizeQuery)
 {
 	Relation relation = NULL;
-	Relation pgDistNode = NULL;
 	List *workerNodeList = NULL;
 	ListCell *workerNodeCell = NULL;
 	uint64 totalRelationSize = 0;
@@ -175,7 +174,7 @@ DistributedTableSize(Oid relationId, char *sizeQuery)
 
 	ErrorIfNotSuitableToGetSize(relationId);
 
-	pgDistNode = heap_open(DistNodeRelationId(), AccessShareLock);
+	LockRelationOid(DistNodeRelationId(), AccessShareLock);
 
 	workerNodeList = ActivePrimaryNodeList();
 
@@ -187,7 +186,6 @@ DistributedTableSize(Oid relationId, char *sizeQuery)
 		totalRelationSize += relationSizeOnNode;
 	}
 
-	heap_close(pgDistNode, NoLock);
 	heap_close(relation, AccessShareLock);
 
 	return totalRelationSize;