moving data files online

oracle 12c introduced a nice feature: move data files online:

SQL*Plus: Release 12.1.0.1.0 Production on Fri Jun 28 16:48:29 2013

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Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL> create tablespace tbs1 datafile '/oradata/dbs300/dbf/tbs1_01.dbf' size 10m;

Tablespace created.

SQL> alter database move datafile '/oradata/dbs300/dbf/tbs1_01.dbf' to '/oradata/dbs300/dbf/tbs1_02.dbf';

Database altered.

SQL> 

the trace file generated gives some more details about the move operation:

Moving datafile /oradata/dbs300/dbf/tbs1_01.dbf (16) to /oradata/dbs300/dbf/tbs1_02.dbf
The secondary file /oradata/dbs300/dbf/tbs1_02.dbf is created
Blocks copied for file /oradata/dbs300/dbf/tbs1_02.dbf
Move operation committed for file /oradata/dbs300/dbf/tbs1_02.dbf
Move operation completed for file /oradata/dbs300/dbf/tbs1_02.dbf
Moving datafile /oradata/dbs300/dbf/tbs1_01.dbf (16) to /oradata/dbs300/dbf/tbs1_02.dbf

*** 2013-06-28 17:28:26.437
The secondary file /oradata/dbs300/dbf/tbs1_02.dbf is created

The number in brackets (16) is the file id:

SQL> select FILE_ID from dba_data_files where file_name = '/oradata/dbs300/dbf/tbs1_02.dbf';

   FILE_ID
----------
	16

SQL>