Recover lost datafile without valid backup

How to recover lost datafile when you don’t have valid backup of your database. Your database is running in archivelog mode and you have all necessary archive logs (... which means since the datafile creation).

SQL> select count(*) from bigtab;
select count(*) from bigtab
*
ERROR at line 1:
ORA-01116: error in opening database file 8
ORA-01110: data file 8: '/u01/oradata/orcl/ts_test01.dbf'
ORA-27041: unable to open file

SQL> alter database datafile 8 offline drop;

SQL> alter database create datafile '/u01/oradata/orcl/ts_test01.dbf' 
                                 as '/u01/oradata/orcl/ts_test01.dbf';

SQL> recover datafile 8;

SQL> alter database datafile 8 online;

SQL> select count(*) from bigtab;

  COUNT(*)
----------
   1000000

From: http://msutic.blogspot.ca/2011/06/recover-lost-datafile-without-valid.html

Use the CREATE DATAFILE clause to create a new empty data file in place of an old one. You can use this clause to re-create a data file that was lost with no backup. The filename or filenumber must identify a file that is or was once part of the database. If you identify the file by number, then filenumber is an integer representing the number found in the FILE# column of the V$DATAFILE dynamic performance view or in the FILE_ID column of the DBA_DATA_FILES data dictionary view.

Specify AS NEW to create an Oracle-managed data file with a system-generated filename, the same size as the file being replaced, in the default file system location for data files.

Specify AS file_specification to assign a file name (and optional size) to the new data file. Use the datafile_tempfile_spec form of file_specification (see file_specification) to list regular data files and temp files in an operating system file system or to list Oracle Automatic Storage Management (Oracle ASM) disk group files.

If the original file (filename or filenumber) is an existing Oracle-managed data file, then Oracle Database attempts to delete the original file after creating the new file. If the original file is an existing user-managed data file, then Oracle Database does not attempt to delete the original file.

If you omit the AS clause entirely, then Oracle Database creates the new file with the same name and size as the file specified by filename or filenumber.

During recovery, all archived redo logs written to since the original data file was created must be applied to the new, empty version of the lost data file.

Oracle Database creates the new file in the same state as the old file when it was created. You must perform media recovery on the new file to return it to the state of the old file at the time it was lost.

From: Alter database create datafile (Oracle® Database SQL Language Reference 11g Release 2 (11.2))