diff --git a/src/backend/access/heap/heapam_visibility.c b/src/backend/access/heap/heapam_visibility.c
index 6e353cec227..0119d76b41d 100644
--- a/src/backend/access/heap/heapam_visibility.c
+++ b/src/backend/access/heap/heapam_visibility.c
@@ -112,6 +112,7 @@ markDirty(Buffer buffer, Relation relation, HeapTupleHeader tuple, bool isXmin)
 	 */
 	if (relation == NULL ||
 		RelationGetRelid(relation) < FirstNormalObjectId ||
+		RelationGetNamespace(relation) == PG_EXTAUX_NAMESPACE ||
 		RelationGetNamespace(relation) == PG_AOSEGMENT_NAMESPACE)
 	{
 		MarkBufferDirtyHint(buffer, true);
diff --git a/src/backend/catalog/catalog.c b/src/backend/catalog/catalog.c
index c5cd2252c84..81b9ebf44ba 100644
--- a/src/backend/catalog/catalog.c
+++ b/src/backend/catalog/catalog.c
@@ -82,6 +82,7 @@
 #endif
 
 static bool IsAoSegmentClass(Form_pg_class reltuple);
+static bool IsExtAuxClass(Form_pg_class reltuple);
 
 /*
  * Like relpath(), but gets the directory containing the data file
@@ -179,6 +180,7 @@ IsSystemClass(Oid relid, Form_pg_class reltuple)
 {
 	/* IsCatalogRelationOid is a bit faster, so test that first */
 	return (IsCatalogRelationOid(relid) || IsToastClass(reltuple) ||
+			IsExtAuxClass(reltuple) ||
 			IsAoSegmentClass(reltuple));
 }
 
@@ -285,6 +287,14 @@ IsAoSegmentClass(Form_pg_class reltuple)
 	return IsAoSegmentNamespace(relnamespace);
 }
 
+static bool
+IsExtAuxClass(Form_pg_class reltuple)
+{
+	Oid			relnamespace = reltuple->relnamespace;
+
+	return IsExtAuxNamespace(relnamespace);
+}
+
 /*
  * IsCatalogNamespace
  *		True iff namespace is pg_catalog.
@@ -332,6 +342,12 @@ IsAoSegmentNamespace(Oid namespaceId)
 	return namespaceId == PG_AOSEGMENT_NAMESPACE;
 }
 
+bool
+IsExtAuxNamespace(Oid namespaceId)
+{
+	return namespaceId == PG_EXTAUX_NAMESPACE;
+}
+
 /*
  * IsReservedName
  *		True iff name starts with the pg_ prefix.
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index c1672f56ad7..11079376ae2 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -1663,8 +1663,9 @@ heap_create_with_catalog(const char *relname,
 		  relkind == RELKIND_PARTITIONED_INDEX ||
 		  relkind == RELKIND_AOSEGMENTS ||
 		  relkind == RELKIND_AOBLOCKDIR ||
-		  relkind == RELKIND_AOVISIMAP) &&
-		relnamespace != PG_BITMAPINDEX_NAMESPACE)
+		  relkind == RELKIND_AOVISIMAP ||
+		  relnamespace == PG_BITMAPINDEX_NAMESPACE ||
+		  relnamespace == PG_EXTAUX_NAMESPACE))
 	{
 		/* OK, so pre-assign a type OID for the array type */
 		Oid			new_array_oid;
@@ -1934,6 +1935,7 @@ heap_create_with_catalog(const char *relname,
 			case PG_TOAST_NAMESPACE:
 			case PG_BITMAPINDEX_NAMESPACE:
 			case PG_AOSEGMENT_NAMESPACE:
+			case PG_EXTAUX_NAMESPACE:
 				doIt = false;
 				break;
 			default:
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index d5489ddf3a4..cb5ff640b52 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -1104,6 +1104,7 @@ index_create_internal(Relation heapRelation,
 			case PG_TOAST_NAMESPACE:
 			case PG_BITMAPINDEX_NAMESPACE:
 			case PG_AOSEGMENT_NAMESPACE:
+			case PG_EXTAUX_NAMESPACE:
 				doIt = false;
 				break;
 			default:
@@ -4011,6 +4012,7 @@ reindex_index(Oid indexId, bool skip_constraint_checks, char persistence,
 			case PG_TOAST_NAMESPACE:
 			case PG_BITMAPINDEX_NAMESPACE:
 			case PG_AOSEGMENT_NAMESPACE:
+			case PG_EXTAUX_NAMESPACE:
 				doIt = false;
 				break;
 			default:
diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index 4f51daaffda..6c5891ce2dd 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -3060,6 +3060,12 @@ CheckSetNamespace(Oid oldNspOid, Oid nspOid)
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("cannot move objects into or out of AO SEGMENT schema")));
+
+	/* same for EXT AUX schema */
+	if (nspOid == PG_EXTAUX_NAMESPACE || oldNspOid == PG_EXTAUX_NAMESPACE)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot move objects into or out of namespace pg_ext_aux")));
 }
 
 /*
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index eac95eeb920..9c18ec27807 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -1519,6 +1519,7 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 #define METATRACK_VALIDNAMESPACE(namespaceId) \
 	(namespaceId != PG_TOAST_NAMESPACE &&	\
 	 namespaceId != PG_BITMAPINDEX_NAMESPACE && \
+	 namespaceId != PG_EXTAUX_NAMESPACE && \
 	 namespaceId != PG_AOSEGMENT_NAMESPACE )
 
 /* check for valid namespace and valid relkind */
@@ -15263,6 +15264,7 @@ ATExecChangeOwner(Oid relationOid, Oid newOwnerId, bool recursing, LOCKMODE lock
 			tuple_class->relkind == RELKIND_PARTITIONED_TABLE ||
 			tuple_class->relkind == RELKIND_MATVIEW ||
 			tuple_class->relkind == RELKIND_TOASTVALUE ||
+			tuple_class->relnamespace == PG_EXTAUX_NAMESPACE ||
 			IsAppendonlyMetadataRelkind(tuple_class->relkind))
 		{
 			List	   *index_oid_list;
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 583d84efbcb..b48e002b988 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -3324,6 +3324,7 @@ vacuumStatement_IsTemporary(Relation onerel)
 		case PG_TOAST_NAMESPACE:
 		case PG_BITMAPINDEX_NAMESPACE:
 		case PG_AOSEGMENT_NAMESPACE:
+		case PG_EXTAUX_NAMESPACE:
 			bTemp = true;
 			break;
 		default:
diff --git a/src/include/catalog/catalog.h b/src/include/catalog/catalog.h
index 11656cf1ebf..a7e77faf8c8 100644
--- a/src/include/catalog/catalog.h
+++ b/src/include/catalog/catalog.h
@@ -40,6 +40,7 @@ extern bool IsCatalogRelationOid(Oid relid);
 extern bool IsCatalogNamespace(Oid namespaceId);
 extern bool IsToastNamespace(Oid namespaceId);
 extern bool IsAoSegmentNamespace(Oid namespaceId);
+extern bool IsExtAuxNamespace(Oid namespaceId);
 
 extern bool IsReservedName(const char *name);
 extern char* GetReservedPrefix(const char *name);
diff --git a/src/include/catalog/pg_namespace.dat b/src/include/catalog/pg_namespace.dat
index b508a4b2d0a..c393b525196 100644
--- a/src/include/catalog/pg_namespace.dat
+++ b/src/include/catalog/pg_namespace.dat
@@ -37,6 +37,9 @@
 { oid => '7012', oid_symbol => 'PG_BITMAPINDEX_NAMESPACE',
   descr => 'Reserved schema for internal relations of bitmap indexes',
   nspname => 'pg_bitmapindex', nspacl => '_null_' },
+{ oid => '7094', oid_symbol => 'PG_EXTAUX_NAMESPACE',
+  descr => 'Reserved schema for internal relations for extensions',
+  nspname => 'pg_ext_aux', nspacl => '_null_' },
 
 # prototypes for functions in pg_namespace.c
 
diff --git a/src/include/catalog/pg_namespace.h b/src/include/catalog/pg_namespace.h
index 51caec0aef6..344211a830b 100644
--- a/src/include/catalog/pg_namespace.h
+++ b/src/include/catalog/pg_namespace.h
@@ -57,8 +57,9 @@ typedef FormData_pg_namespace *Form_pg_namespace;
 #define IsBuiltInNameSpace(namespaceId) \
 	(namespaceId == PG_CATALOG_NAMESPACE || \
 	 namespaceId == PG_TOAST_NAMESPACE || \
-	 namespaceId == PG_BITMAPINDEX_NAMESPACE || \
 	 namespaceId == PG_PUBLIC_NAMESPACE || \
+	 namespaceId == PG_EXTAUX_NAMESPACE || \
+	 namespaceId == PG_BITMAPINDEX_NAMESPACE || \
 	 namespaceId == PG_AOSEGMENT_NAMESPACE)
 
 DECLARE_TOAST(pg_namespace, 4163, 4164);