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前面介绍了4种推进SCN方法
（1）event 10015 来增加 scn 的值
（2）隐含参数_minimum_giga_scn 来增加 scn 的值
（3）gdb/dbx 来直接修改内存中的值
（4）使用oradebug poke 直接修改内存中的值
（5）通过修改控制文件来修改 scn 的值
现在来说一下oracle推进SCN方法6：通过修改数据文件头来修改 scn 的值
1、查看当前SCN
--最好将数据库启动到mount状态
SQL> startup mount;
ORACLE instance started.
Total System Global Area 3691200512 bytes
Fixed Size 2258680 bytes
Variable Size 788531464 bytes
Database Buffers 2885681152 bytes
Redo Buffers 14729216 bytes
Database mounted.
SQL> select checkpoint_change# from v$database;
CHECKPOINT_CHANGE#
------------------
3433886
SQL> col name for a80
SQL> set linesize 400;
SQL> select file#,name from v$datafile;
FILE# NAME
---------- --------------------------------------------------------------------------------
1 /u01/oradata/dbbbed/system01.dbf
2 /u01/oradata/dbbbed/sysaux01.dbf
3 /u01/oradata/dbbbed/undotbs01.dbf
4 /u01/oradata/dbbbed/users01.dbf
5 /u01/oradata/dbbbed/tbst01.dbf
6 /u01/oradata/dbbbed/szr01.dbf
7 /u01/oradata/dbbbed/mssm01.dbf
8 /u01/oradata/dbbbed/test0529.dbf
8 rows selected.
SQL> col name for a60;
set linesize 400;
select a.file#,
a.name,
(select checkpoint_change# from v$database) system_ckpt_scn,
a.checkpoint_change# df_ckpt_scn,
a.last_change# end_scn,
b.checkpoint_change# start_scn,
b.rSQL> SQL> 2 3 4 5 6 7 ecover,
a.status
from v$datafile a, v$datafile_header b
where a.file# = b.file#; 8 9 10
FILE# NAME SYSTEM_CKPT_SCN DF_CKPT_SCN END_SCN START_SCN REC STATUS
---------- ------------------------------------------------------------ --------------- ----------- ---------- ---------- --- -------
1 /u01/oradata/dbbbed/system01.dbf 3433886 3433886 3433886 3433886 NO SYSTEM
2 /u01/oradata/dbbbed/sysaux01.dbf 3433886 3433886 3433886 3433886 NO ONLINE
3 /u01/oradata/dbbbed/undotbs01.dbf 3433886 3433886 3433886 3433886 NO ONLINE
4 /u01/oradata/dbbbed/users01.dbf 3433886 3433886 3433886 3433886 NO ONLINE
5 /u01/oradata/dbbbed/tbst01.dbf 3433886 3433886 3433886 3433886 NO ONLINE
6 /u01/oradata/dbbbed/szr01.dbf 3433886 3433886 3433886 3433886 NO ONLINE
7 /u01/oradata/dbbbed/mssm01.dbf 3433886 3433886 3433886 3433886 NO ONLINE
8 /u01/oradata/dbbbed/test0529.dbf 3433886 3433886 3433886 3433886 NO ONLINE
2、bbed修改文件头SCN
–将数据文件加入bbed filelist,使用bbed进行编辑
$ cat filelist.txt
1 /u01/oradata/dbbbed/system01.dbf 775946240
2 /u01/oradata/dbbbed/sysaux01.dbf 513802240
3 /u01/oradata/dbbbed/undotbs01.dbf 78643200
4 /u01/oradata/dbbbed/users01.dbf 5242880
5 /u01/oradata/dbbbed/tbst01.dbf 10485760
6 /u01/oradata/dbbbed/szr01.dbf 10485760
7 /u01/oradata/dbbbed/mssm01.dbf 10485760
8 /u01/oradata/dbbbed/test0529.dbf 5242880
$ bbed
BBED: Release 2.0.0.0.0 - Limited Production on Thu Jun 6 11:01:03 2024
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
************* !!! For Oracle Internal Use only !!! ***************
BBED> info
File# Name Size(blks)
----- ---- ----------
1 /u01/oradata/dbbbed/system01.dbf 94720
2 /u01/oradata/dbbbed/sysaux01.dbf 62720
3 /u01/oradata/dbbbed/undotbs01.dbf 9600
4 /u01/oradata/dbbbed/users01.dbf 640
5 /u01/oradata/dbbbed/tbst01.dbf 1280
6 /u01/oradata/dbbbed/szr01.dbf 1280
7 /u01/oradata/dbbbed/mssm01.dbf 1280
8 /u01/oradata/dbbbed/test0529.dbf 640
–将所有数据文件头的scn由3433886改成4433886
SQL> select to_char(3433886,'xxxxxxxxxxx'),to_char(4433886,'xxxxxxxxxxxx') from dual;
TO_CHAR(3433 TO_CHAR(44338
------------ -------------
34659e 43a7de
BBED> set file 1 block 1
FILE# 1
BLOCK# 1
BBED> p kcvfhckp
struct kcvfhckp, 36 bytes @484
struct kcvcpscn, 8 bytes @484
ub4 kscnbas @484 0x0034659e
ub2 kscnwrp @488 0x0000
ub4 kcvcptim @492 0x45cb01f0
ub2 kcvcpthr @496 0x0001
union u, 12 bytes @500
struct kcvcprba, 12 bytes @500
ub4 kcrbaseq @500 0x00000007
ub4 kcrbabno @504 0x00000223
ub2 kcrbabof @508 0x0010
##注意上面的红色字体部分，我们需要将offset 484 这个地方的值改成0x0043a7de
BBED> assign dba 1,1 kcvfh.kcvfhckp.kcvcpscn.kscnbas = 0x0043a7de
或者直接用10进制的也行
BBED> assign dba 1,1 kcvfh.kcvfhckp.kcvcpscn.kscnbas = 4433886
Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) y
ub4 kscnbas @484 0x0043a7de
BBED> p kcvfhckp
struct kcvfhckp, 36 bytes @484
struct kcvcpscn, 8 bytes @484
ub4 kscnbas @484 0x0043a7de
继续修改其他的数据文件
assign dba 2,1 kcvfh.kcvfhckp.kcvcpscn.kscnbas = 0x0043a7de
assign dba 3,1 kcvfh.kcvfhckp.kcvcpscn.kscnbas = 0x0043a7de
assign dba 4,1 kcvfh.kcvfhckp.kcvcpscn.kscnbas = 0x0043a7de
assign dba 5,1 kcvfh.kcvfhckp.kcvcpscn.kscnbas = 0x0043a7de
assign dba 6,1 kcvfh.kcvfhckp.kcvcpscn.kscnbas = 0x0043a7de
assign dba 7,1 kcvfh.kcvfhckp.kcvcpscn.kscnbas = 0x0043a7de
assign dba 8,1 kcvfh.kcvfhckp.kcvcpscn.kscnbas = 0x0043a7de
–保存修改
BBED> sum apply dba 1,1
Check value for File 1, Block 1:
current = 0x73a2, required = 0x73a2
BBED> sum apply dba 2,1
Check value for File 2, Block 1:
current = 0x06ea, required = 0x06ea
BBED> sum apply dba 3,1
Check value for File 3, Block 1:
current = 0x2aca, required = 0x2aca
BBED> sum apply dba 4,1
Check value for File 4, Block 1:
current = 0x44a3, required = 0x44a3
BBED> sum apply dba 5,1
Check value for File 5, Block 1:
current = 0x4dbe, required = 0x4dbe
BBED> sum apply dba 6,1
Check value for File 6, Block 1:
current = 0x4c4b, required = 0x4c4b
BBED> sum apply dba 7,1
Check value for File 7, Block 1:
current = 0x7012, required = 0x7012
BBED> sum apply dba 8,1
Check value for File 8, Block 1:
current = 0xa710, required = 0xa710
3、查看修改后的SCN
--打开数据库
SQL> alter database open;
Database altered.
--查看数据文件头的scn
SQL> select checkpoint_change# from v$datafile_header;
CHECKPOINT_CHANGE#
------------------
4433887
4433887
4433887
4433887
4433887
4433887
4433887
4433887
8 rows selected.
SQL> col name for a60;
set linesize 400;
select a.file#,
a.name,
(select checkpoint_change# from v$database) system_ckpt_scn,
a.checkpoint_change# df_ckpt_scn,
a.last_change# end_scn,
b.checkpoint_change# start_scn,
b.rSQL> SQL> 2 3 4 5 6 7 ecover,
a.status
from v$datafile a, v$datafile_header b
where a.file# = b.file#; 8 9 10
FILE# NAME SYSTEM_CKPT_SCN DF_CKPT_SCN END_SCN START_SCN REC STATUS
---------- ------------------------------------------------------------ --------------- ----------- ---------- ---------- --- -------
1 /u01/oradata/dbbbed/system01.dbf 4433887 4433887 4433887 NO SYSTEM
2 /u01/oradata/dbbbed/sysaux01.dbf 4433887 4433887 4433887 NO ONLINE
3 /u01/oradata/dbbbed/undotbs01.dbf 4433887 4433887 4433887 NO ONLINE
4 /u01/oradata/dbbbed/users01.dbf 4433887 4433887 4433887 NO ONLINE
5 /u01/oradata/dbbbed/tbst01.dbf 4433887 4433887 4433887 NO ONLINE
6 /u01/oradata/dbbbed/szr01.dbf 4433887 4433887 4433887 NO ONLINE
7 /u01/oradata/dbbbed/mssm01.dbf 4433887 4433887 4433887 NO ONLINE
8 /u01/oradata/dbbbed/test0529.dbf 4433887 4433887 4433887 NO ONLINE
8 rows selected.
--查看数据库的scn
SQL> select current_scn from v$database;
CURRENT_SCN
-----------
4434186
可以看到，SCN已修改，成功推进SCN。
链接：
史上最全，呕心沥血总结oracle推进SCN方法（一）
史上最全，呕心沥血总结oracle推进SCN方法（二）
史上最全，呕心沥血总结oracle推进SCN方法（三）
史上最全，呕心沥血总结oracle推进SCN方法（四）
史上最全，呕心沥血总结oracle推进SCN方法（五）
