delayed block cleanout的例子：

SQL> select * from tt

ID NAME

---------- --------------------

1 xxxxxxx

2 xxxxxxx

3 xxxxxxx

SQL> update tt set name='111111111' where id=1;

1 row updated.

SQL> update tt set name='222222222222' where id=2;

1 row updated.

SQL> update tt set name='3333333333' where id=3;

1 row updated.

SQL> alter session set events 'immediate trace name flush_cache';

Session altered.

SQL> commit;

Commit complete.

SQL> alter system dump datafile 4 block 92;

System altered.

查看dump出来的内容之后，发现block中海油ITL的信息。如下为block dump的信息:

---===========================================

Itl Xid Uba Flag Lck Scn/Fsc

0x01 0x0005.003.00000383 0x00801a95.012b.15 --U- 3 fsc 0x0000.00194a1e

0x02 0x0008.015.00000385 0x00800204.0123.03 C--- 0 scn 0x0000.001949e9

data_block_dump,data header at 0x8ee5264

===============

tsiz: 0x1f98

hsiz: 0x18

pbl: 0x08ee5264

bdba: 0x0100005c

76543210

flag=--------

ntab=1

nrow=3

frre=-1

fsbo=0x18

fseo=0x1f16

avsp=0x1f4c

tosp=0x1f4c

0xe:pti[0] nrow=3 offs=0

0x12:pri[0] offs=0x1f3a

0x14:pri[1] offs=0x1f27

0x16:pri[2] offs=0x1f16

block_row_dump:

tab 0, row 0, @0x1f3a

tl: 16 fb: --H-FL-- lb: 0x1 cc: 2

col 0: [ 2] c1 02

col 1: [ 9] 31 31 31 31 31 31 31 31 31

tab 0, row 1, @0x1f27

tl: 19 fb: --H-FL-- lb: 0x1 cc: 2

col 0: [ 2] c1 03

col 1: [12] 32 32 32 32 32 32 32 32 32 32 32 32

tab 0, row 2, @0x1f16

tl: 17 fb: --H-FL-- lb: 0x1 cc: 2

col 0: [ 2] c1 04

col 1: [10] 33 33 33 33 33 33 33 33 33 33

end_of_block_dump

End dump data blocks tsn: 4 file#: 4 minblk 92 maxblk 92

---=====================================================

下次访问更新的时候，就可以清除。