[测试相关] 创建随机数据

create table t(a number,b varchar2(80));

begin
for i in 1 .. 100000
  loop
    insert into t (a,b) values (i,rpad(dbms_random.random,75,'*')); --- b列的数据是随机的
  end loop;
end;
/

alter table t add constraint t_pk primary key (a);

select avg(lengthb(a)+lengthb(b)) from t; --- t表中的数据每行长度大约为80字节

begin
    dbms_stats.gather_table_stats(user,'T',cascade=>true);
end;
/

create table tt as select a,b from t order by b;

alter table tt add constraint tt_pk primary key (a);

begin
    dbms_stats.gather_table_stats(user,'TT',cascade=>true);
end;
/