getObjectDescription: support extended statistics

This was missed in 7b504eb2.

Remove the "default:" clause in the switch, to avoid this problem in the
future.  Other switches involving the same enum should probably be
changed in the same way, but are not touched by this patch.

Discussion: https://postgr.es/m/20170512204800.iqt2uwyx3c32j45r@alvherre.pgsql

src/backend/catalog/objectaddress.c

@@ -3004,6 +3004,26 @@ getObjectDescription(const ObjectAddress *object)
 				break;
 			}
 
+		case OCLASS_STATISTIC_EXT:
+			{
+				HeapTuple	stxTup;
+				Form_pg_statistic_ext stxForm;
+
+				stxTup = SearchSysCache1(STATEXTOID,
+										 ObjectIdGetDatum(object->objectId));
+				if (!HeapTupleIsValid(stxTup))
+					elog(ERROR, "could not find tuple for statistics object %u",
+						 object->objectId);
+
+				stxForm = (Form_pg_statistic_ext) GETSTRUCT(stxTup);
+
+				appendStringInfo(&buffer, _("statistics object %s"),
+								 NameStr(stxForm->stxname));
+
+				ReleaseSysCache(stxTup);
+				break;
+			}
+
 		case OCLASS_TRANSFORM:
 			{
 				HeapTuple	trfTup;
@@ -3394,13 +3414,6 @@ getObjectDescription(const ObjectAddress *object)
 								 get_subscription_name(object->objectId));
 				break;
 			}
-
-		default:
-			appendStringInfo(&buffer, "unrecognized object %u %u %d",
-							 object->classId,
-							 object->objectId,
-							 object->objectSubId);
-			break;
 	}
 
 	return buffer.data;