oracle11g
观察数据库scn:
SQL> select dbms_flashback.get_system_change_number from dual;
GET_SYSTEM_CHANGE_NUMBER
------------------------
1025713
SQL> select checkpoint_change# from v$database;
CHECKPOINT_CHANGE#
------------------
1022214
SQL>
********************************
强制执行checkpoint:
SQL> alter system checkpoint;
System altered.
SQL> select checkpoint_change# from v$database;
CHECKPOINT_CHANGE#
------------------
1025732
可以看到，此时 checkpoint_change# 比刚才的数据库scn 要大一些。这是因为数据库scn 随着时间的增长而增长。
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>