Taking a Datafile Offline in NOARCHIVELOG Mode

I read some RMAN documentation which said that you could not take a datafile offline if the database was in NOARCHIVELOG mode. I don’t know much about taking datafiles offline but this seemed reasonable so I gave it a try in Oracle 12.1. First I checked the database’s LOG_MODE: 

SQL> select log_mode from v$database

  2  /

 

LOG_MODE

------------

NOARCHIVELOG

 

SQL>

Then I tried to take a datafile offline but this failed, as the documentation had said it would: 

SQL> alter database datafile

  2  'C:\APP\ADMINISTRATOR\ORADATA\ORCL1\DATAFILE\USERS.DBF'

  3  offline

  4  /

alter database datafile

*

ERROR at line 1:

ORA-01145: offline immediate disallowed unless media

recovery enabled

 

SQL>

 

I read somewhere in the Oracle documentation that you could do this if the tablespace was READ ONLY. This also seemed reasonable so I tried it too: 

SQL> alter tablespace users read only

  2  /

 

Tablespace altered.

 

SQL> alter database datafile

  2  'C:\APP\ADMINISTRATOR\ORADATA\ORCL1\DATAFILE\USERS.DBF'

  3  offline

  4  /

 

Database altered.

 

SQL> 

Of course, once I had done this, I could not change the tablespace to READ WRITE mode again: 

SQL> l

  1* alter tablespace users read write

SQL> /

alter tablespace users read write

*

ERROR at line 1:

ORA-01135: file 6 accessed for DML/query is offline

ORA-01110: data file 6:

'C:\APP\ADMINISTRATOR\ORADATA\ORCL1\DATAFILE\USERS.DBF'

 

SQL> 

… until I had brought the datafile ONLINE: 

SQL> alter database datafile

  2  'C:\APP\ADMINISTRATOR\ORADATA\ORCL1\DATAFILE\USERS.DBF'

  3  online

  4  /

 

Database altered.

 

SQL> alter tablespace users read write

  2  /

 

Tablespace altered.

 

SQL>