--1、建一个和A表一模一样的临时表,并在hello上建索引
create table tmp_A as select * from A where 1=2;
create index tmp_a_idx1 on tmp_a(hello);
--2、建立一个临时表tmp_b B表hello字段替冲，并加索引
create table tmp_B as select distinct hello from B;
create index tmp_b_idx1 on tmp_b(hello);

--3、从A表中随即查出10W条 hello字段不重复的数据插入临时表 tmp_A
INSERT INTO TMP_A
  SELECT 列出A表字段
    FROM (SELECT A.*,
                 ROW_NUMBER() OVER(PARTITION BY A.HELLO ORDER BY DBMS_RANDOM.VALUE) ROW_
            FROM A
           WHERE NOT EXISTS
           (SELECT 1 FROM TMP_B WHERE A.HELLO = TMP_B.HELLO))
   WHERE ROW_ = 1
     AND ROWNUM <= 100000;

--4、将临时表Tmp_a中数据插入B表
insert into B select * from Tmp_a;