oracle里tablespace offline和datafile offline的区别

网上搜了几篇关于tablespace offline 和 datafile offline区别的文章，小总结了一下，记下来，方便以后学习。
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There is a big difference between:
Taking the tablespace offline and Taking the datafiles offline
ALTER TABLESPACE ... OFFLINE
Does a checkpoint on the datafiles
Takes the datafiles offline
(从EM中可以看到tablespace offline有几种选项可供选择normal, temporary,immediate, for recovery,而在datafile中则没有这些选项)
SQL>select dbms_flashback.get_system_change_number from dual;
GET_SYSTEM_CHANGE_NUMBER
------------------------
27259186261
SQL>alter tablespace block offline;
表空间已更改
SQL>select file#,name,checkpoint_change# from v$datafile;
FILE# NAME CHECKPOINT_CHANGE#
......
13 F:\ORACLE\ORADATA\TEST\RMAN.DBF 27259134244
14 F:\ORACLE\ORADATA\TEST\MAGGIE_DATA1.DBF 27207207995
15 F:\ORACLE\ORADATA\TEST\BLOCK01.DBF 27259186316
SQL>select dbms_flashback.get_system_change_number from dual;
GET_SYSTEM_CHANGE_NUMBER
------------------------
27259186335
SQL>alter tablespace block online;
表空间已更改
SQL>select file#,name,checkpoint_change# from v$datafile;
FILE# NAME CHECKPOINT_CHANGE#
......
13 F:\ORACLE\ORADATA\TEST\RMAN.DBF 27259134244
14 F:\ORACLE\ORADATA\TEST\MAGGIE_DATA1.DBF 27207207995
15 F:\ORACLE\ORADATA\TEST\BLOCK01.DBF 27259186345
SQL>select dbms_flashback.get_system_change_number from dual;
GET_SYSTEM_CHANGE_NUMBER
------------------------
27259186378

ALTER DATABASE DATAFILE ... OFFLINE
Does not perform. a checkpoint,
So that if the database is open, you may need to perform. media recovery when bringing it online.
SQL>select file#,name,checkpoint_change# from v$datafile;
FILE# NAME CHECKPOINT_CHANGE#
......
13 F:\ORACLE\ORADATA\TEST\RMAN.DBF27259134244
14 F:\ORACLE\ORADATA\TEST\MAGGIE_DATA1.DBF27207207995
15 F:\ORACLE\ORADATA\TEST\BLOCK01.DBF 27259134244
SQL>select dbms_flashback.get_