oracle11g

觀察數據庫scn:

SQL> select dbms_flashback.get_system_change_number from dual;

GET_SYSTEM_CHANGE_NUMBER
------------------------
???????????????? 1025713

SQL> select checkpoint_change# from v$database;

CHECKPOINT_CHANGE#
------------------
?????????? 1022214

SQL>

********************************

強制執行checkpoint:

SQL> alter system checkpoint;

System altered.

SQL> select checkpoint_change# from v$database;

CHECKPOINT_CHANGE#
------------------
?????????? 1025732
可以看到，此時 checkpoint_change# 比剛才的數據庫scn 要大一些。這是因為數據庫scn 隨著時間的增長而增長。

?

SQL> select dbms_flashback.get_system_change_number from dual;

GET_SYSTEM_CHANGE_NUMBER
------------------------
???????????????? 1025755

SQL> alter system checkpoint;

System altered.

SQL>

?

SQL> select checkpoint_change# from v$database;

CHECKPOINT_CHANGE#
------------------
?????????? 1025765

SQL> select name, checkpoint_change# from v$datafile;???? ?

NAME
--------------------------------------------------------------------------------
CHECKPOINT_CHANGE#
------------------
/u01/app/oracle/oradata/orcl/system01.dbf
?????????? 1025765

/u01/app/oracle/oradata/orcl/sysaux01.dbf
?????????? 1025765

/u01/app/oracle/oradata/orcl/undotbs01.dbf
?????????? 1025765


NAME
--------------------------------------------------------------------------------
CHECKPOINT_CHANGE#
------------------
/u01/app/oracle/oradata/orcl/users01.dbf
?????????? 1025765

/u01/app/oracle/oradata/orcl/example01.dbf
?????????? 1025765


SQL> select name, checkpoint_change# from v$datafile_header;

NAME
--------------------------------------------------------------------------------
CHECKPOINT_CHANGE#
------------------
/u01/app/oracle/oradata/orcl/system01.dbf
?????????? 1025765

/u01/app/oracle/oradata/orcl/sysaux01.dbf
?????????? 1025765

/u01/app/oracle/oradata/orcl/undotbs01.dbf
?????????? 1025765


NAME
--------------------------------------------------------------------------------
CHECKPOINT_CHANGE#
------------------
/u01/app/oracle/oradata/orcl/users01.dbf
?????????? 1025765

/u01/app/oracle/oradata/orcl/example01.dbf
?????????? 1025765


SQL>

本文轉自健哥的數據花園博客園博客，原文鏈接：http://www.cnblogs.com/gaojian/p/3663959.html，如需轉載請自行聯系原作者

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