create table TMP_SERIAL_NBR
(
  serial_nbr NUMBER
);

INsert /*+ append parallel(a,16) */ into tmp_serial_nbr a
 SELECT column_value as serial_nbr FROM TABLE(rowgen(10000000,99999999));


create or replace type numtab_type as table of number;

CREATE OR REPLACE FUNCTION rowgen(p_start_num in number, p_end_num IN NUMBER)
RETURN numtab_type DETERMINISTIC PIPELINED PARALLEL_ENABLE
AS
BEGIN
  -- create or replace type numtab_type as table of number;
  FOR i IN p_start_num..p_end_num
  LOOP
    PIPE ROW(i);
  END LOOP;
  
  RETURN;
END rowgen;

create table final_random_nbr nologging as
SELECT ROWNUM AS SEQ_NBR, SERIAL_NBR
     FROM (  SELECT SERIAL_NBR
               FROM (SELECT /*+ parallel (tsn 16) */
                           SERIAL_NBR,
                            TRUNC (DBMS_RANDOM.VALUE (1, 999999999))
                               AS SORT_RNK
                       FROM TMP_SERIAL_NBR TSN)
           ORDER BY SORT_RNK)
    WHERE ROWNUM <= 40000000