1.在没有热备份前：

SQL> select checkpoint_change# from v$database;

CHECKPOINT_CHANGE#
------------------
1272750703

SQL> select file#,checkpoint_change#,last_change# from v$datafile;

FILE# CHECKPOINT_CHANGE# LAST_CHANGE#
---------- ------------------ ------------
1 1272750703
2 1272750703
3 1272750703
4 1272750703

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

FILE# CHECKPOINT_CHANGE#
---------- ------------------
1 1272750703
2 1272750703
3 1272750703
4 1272750703

2. 开始热备份

SQL> alter tablespace users begin backup;

Tablespace altered.

发出 完全检查点：

SQL> alter system checkpoint;

System altered.

SQL> select checkpoint_change# from v$database;

CHECKPOINT_CHANGE#
------------------
1272764673

SQL> select file#,checkpoint_change#,last_change# from v$datafile;

FILE# CHECKPOINT_CHANGE# LAST_CHANGE#
---------- ------------------ ------------
1 1272764673
2 1272764673
3 1272764673
4 1272764651

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

FILE# CHECKPOINT_CHANGE#
---------- ------------------
1 1272764673
2 1272764673
3 1272764673
4 1272764651

在热备份期间，热备份的表空间scn 保持不变

3。 结束热备份

SQL> alter tablespace users end backup;

4。 查询热备份结束时的scn

SQL> select file#,checkpoint_change#,last_change# from v$datafile;

FILE# CHECKPOINT_CHANGE# LAST_CHANGE#
---------- ------------------ ------------
1 1272764673
2 1272764673
3 1272764673
4 1272764673

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

FILE# CHECKPOINT_CHANGE#
---------- ------------------
1 1272764673
2 1272764673
3 1272764673
4 1272764673

热备份后，数据库各数据文件scn 一致