index block cleanout

I have one question about index block cleanout. When I use two commands to cleanout index block. But it does not work at all.

ALTER SESSION SET EVENTS 'immediate trace name flush_cache'; alter system flush buffer_cache;

Below are my test case

1. create table test_empty_block (id number, value varchar2(10));
2. create index TEST_EMPTY_BLOCK_IDX on test_empty_block (id);

3.
begin
 for i in 1..100000 loop
 insert into test_empty_block values (i, 'Bowie');  end loop;
 commit;
end;
/

4. delete from test_empty_block where id < 99999;

commit;

5. analyze index test_empty_block_idx validate structure;

select * from index_stats;
DEL_LF_ROWS

6.
ALTER SESSION SET EVENTS 'immediate trace name flush_cache'; alter system flush buffer_cache;

7.
analyze index test_empty_block_idx validate structure;

select * from index_stats;
DEL_LF_ROWS

Thanks at first
Jacky Received on Sat Mar 07 2009 - 05:00:56 CST