1、下面是通過視圖來觀察數據文件的一些scn信息
select file#,name,
CREATION_CHANGE#, --創建數據文件時的scn
RESETLOGS_CHANGE#, --最後一次使用resetlog打開數據庫的scn
CHECKPOINT_CHANGE# --數據文件當前scn
from v$datafile_header;
FILE# NAME CREATION_CHANGE# RESETLOGS_CHANGE# CHECKPOINT_CHANGE#
---------- -------------------------------------------------- ---------------- ----------------- ------------------
1 /u01/app/oracle/oradata/normal/system01.dbf 8 1 924853
2 /u01/app/oracle/oradata/normal/undotbs01.dbf 5224 1 924853
3 /u01/app/oracle/oradata/normal/sysaux01.dbf 5349 1 924853
4 /u01/app/oracle/oradata/normal/users01.dbf 5826 1 924853
5 /u01/app/oracle/oradata/normal/chenhao01.dbf 7948 1 924853
6 /u01/app/oracle/oradata/normal/undotbs02.dbf 155204 1 924853
7 /u01/app/oracle/oradata/normal/system02.dbf 517792 1 924853
8 /u01/app/oracle/oradata/normal/outln01.dbf 769957 1 924853
9 /u01/app/oracle/oradata/normal/test01.dbf 818947 1 924853
select FILE#,
CHANGE# --數據文件最後一次做熱備時pin住的scn（使用begin backup備份的）
from v$backup;
FILE# CHANGE#
---------- ----------
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 0
9 0SQL> alter session set events 'immediate trace name file_hdrs level 3';
Session altered.
SQL> alter session set events 'immediate trace name file_hdrs off';
Session altered.Tablespace #0 - SYSTEM rel_fn:1
Creation at scn: 0x0000.00000008 08/21/2014 16:26:11
#創建數據文件時的scn，和v$datafile_header.CREATION_CHANGE#對應
Backup taken at scn: 0x0000.00000000 01/01/1988 00:00:00 thread:0
#數據文件最後一次做熱備時pin住的scn，和#v$backup.CHANGE#對應
reset logs count:0x33088679 scn: 0x0000.00000001
#最後一次使用resetlog打開數據庫的scn，和v$datafile_header.RESETLOGS_CHANGE#對應
prev reset logs count:0x0 scn: 0x0000.00000000
recovered at 08/22/2014 12:54:15
status:0x2004 root dba:0x00402901 chkpt cnt: 133 ctl cnt:132
begin-hot-backup file size: 0
Checkpointed at scn: 0x0000.000e1cb5 08/27/2014 18:00:11
#數據文件當前scn，和v$datafile_header.CHECKPOINT_CHANGE#
3、下面使用bbed來查看這些scn（這裏在11g中怎麼安裝bbed就不說了）
SQL> select file#||' '||name||' '||bytes from v$datafile;
FILE#||''||NAME||''||BYTES
----------------------------------------------------------
1 /u01/app/oracle/oradata/normal/system01.dbf 340787200
2 /u01/app/oracle/oradata/normal/undotbs01.dbf 209715200
3 /u01/app/oracle/oradata/normal/sysaux01.dbf 340787200
4 /u01/app/oracle/oradata/normal/users01.dbf 524288000
5 /u01/app/oracle/oradata/normal/chenhao01.dbf 104857600
6 /u01/app/oracle/oradata/normal/undotbs02.dbf 209715200
7 /u01/app/oracle/oradata/normal/system02.dbf 314572800
8 /u01/app/oracle/oradata/normal/outln01.dbf 20971520
9 /u01/app/oracle/oradata/normal/test01.dbf 10485760
[oracle@normal ~]$ cat filelist.txt
1 /u01/app/oracle/oradata/normal/system01.dbf 340787200
2 /u01/app/oracle/oradata/normal/undotbs01.dbf 209715200
3 /u01/app/oracle/oradata/normal/sysaux01.dbf 340787200
4 /u01/app/oracle/oradata/normal/users01.dbf 524288000
5 /u01/app/oracle/oradata/normal/chenhao01.dbf 104857600
6 /u01/app/oracle/oradata/normal/undotbs02.dbf 209715200
7 /u01/app/oracle/oradata/normal/system02.dbf 314572800
8 /u01/app/oracle/oradata/normal/outln01.dbf 20971520
9 /u01/app/oracle/oradata/normal/test01.dbf 10485760
[oracle@normal ~]$ cat bbed.par
blocksize=8192
listfile=/home/oracle/filelist.txt
mode=edit
[oracle@normal ~]$ bbed parfile=bbed.par
BBED> set dba 1,1
-------------------------------------------------
--先說明以下scn是有basescn、和wrapscn兩部分構成的
-------------------------------------------------
--查看創建數據文件時的scn，和v$datafile_header.CREATION_CHANGE#對應
BBED> print kcvfhcrs
struct kcvfhcrs, 8 bytes @100
ub4 kscnbas @100 0x00000008
ub2 kscnwrp @104 0x0000
--查看#最後一次使用resetlog打開數據庫的scn，和v$datafile_header.RESETLOGS_CHANGE#對應
BBED> print kcvfhrls
struct kcvfhrls, 8 bytes @116
ub4 kscnbas @116 0x00000001
ub2 kscnwrp @120 0x0000
--查看數據文件最後一次做熱備時pin住的scn，和#v$backup.CHANGE#對應
BBED> print kcvfhbsc
struct kcvfhbsc, 8 bytes @128
ub4 kscnbas @128 0x00000000
ub2 kscnwrp @132 0x0000
--查看數據文件當前scn，和v$datafile_header.CHECKPOINT_CHANGE#
BBED> print kcvfhckp
struct kcvfhckp, 36 bytes @484
struct kcvcpscn, 8 bytes @484
ub4 kscnbas @484 0x000e1cb5
ub2 kscnwrp @488 0x0000
-------------------------------------------------------------
--通過上面顯示的偏移量(offset,如:@100)我們來看看具體呈現的樣子
--這裏只做數據文件創建時scn的例子。
--------------------------------------------------------------
BBED> set dba 1,1
DBA 0x00400001 (4194305 1,1)
BBED> dump offset 100 count 8
File: /u01/app/oracle/oradata/normal/system01.dbf (1)
Block: 1 Offsets: 100 to 115 Dba:0x00400001
------------------------------------------------------------------------
08000000 00000000 --這裏由於大小端的問題需要倒過來看 如:08000000 -> 00000008
<32 bytes per line>
