Unlike in the previous releases, a data file migration or renaming in Oracle database 12c R1 no longer requires a number of steps i.e. putting the tablespace in READ ONLY mode, followed by data file offline action.
In 12c R1, a data file can be renamed or moved online simply using the ALTER DATABASE MOVE DATAFILE SQL statement. While the data file is being transferred, the end user can perform queries, DML and DDL tasks. Additionally, data files can be migrated between storages e.g. from non-ASM to ASM and vice versa.
Rename a data file:
SQL> ALTER DATABASE MOVE DATAFILE '/u01/data/users01.dbf' TO '/u00/data/users_01.dbf';
Migrate a data file from non-ASM to ASM:
SQL> ALTER DATABASE MOVE DATAFILE '/u01/data/users_01.dbf' TO '+DG_DATA';
Migrate a data file from one ASM disk group to another:
SQL> ALTER DATABASE MOVE DATAFILE '+DG_DATA/DBNAME/DATAFILE/users_01.dbf ' TO '+DG_DATA_02';
Overwrite the data file with the same name, if it exists at the new location:
SQL> ALTER DATABASE MOVE DATAFILE '/u00/data/users_01.dbf' TO '/u00/data_new/users_01.dbf' REUSE;
Copy the file to a new location whilst retaining the old copy in the old location:
SQL> ALTER DATABASE MOVE DATAFILE '/u00/data/users_01.dbf' TO '/u00/data_new/users_01.dbf' KEEP;
You can monitor the progress while a data file being moved by querying the v$session_longops dynamic view. Additionally, you can also refer the alert.log of the database where Oracle writes the details about action being taken place.