oracle查索引大小

文档课题：oracle查索引大小.
数据库：oracle 11.2.0.4 64位
以下为实际操作过程.
SQL> create table emp_init(
  2      id number(12),
  3      name varchar2(20),
  4      age number(3),
  5      salary number(6),
  6      create_time timestamp default sysdate,
  7      remark nvarchar2(100),
  8      primary key(id));

Table created.

Elapsed: 00:00:00.07
SQL> insert into emp_init
  2    select rownum,
  3           dbms_random.string('*', dbms_random.value(6, 20)),
  4           dbms_random.value(18, 65),
  5           dbms_random.value(1000, 50000),
  6           sysdate,
  7           dbms_random.string('*', dbms_random.value(10, 100))
  8      from dual
  9    connect by level < 4001;

4000 rows created.

Elapsed: 00:00:00.83
SQL> commit;

Commit complete.

Elapsed: 00:00:00.00
SQL> create index ind_emp_init_date on emp_init (create_time);

Index created.

Elapsed: 00:00:00.01
SQL> select blocks,bytes from dba_segments where owner='SYS' and segment_name='IND_EMP_INIT_DATE';

    BLOCKS      BYTES
---------- ----------
        16     131072

SQL> select blocks,bytes from dba_segments where owner='SYS' and segment_name='EMP_INIT';

    BLOCKS      BYTES
---------- ----------
        88     720896