在业务不间断下修改索引

declare
  resource_busy exception;
  pragma exception_init (resource_busy,-54);
begin
loop
   begin
     execute immediate 'Alter index IDX_TB_TEST2_N1 noparallel';
     exit;
   exception
    when resource_busy then
     dbms_lock.sleep(1);
   end;
end loop;
end;