Operation of Oracle Managed Files

The filenames of Oracle Managed Files are accepted in SQL statements wherever a filename is used to identify an existing file. These filenames, like other filenames, are stored in the control file and, if using Recovery Manager (RMAN) for backup and recovery, in the RMAN catalog. They are visible in all of the usual fixed and dynamic performance views that are available for monitoring datafiles and tempfiles (for example, V$DATAFILE or DBA_DATA_FILES).

The following are some examples of statements using database-generated filenames:

SQL> ALTER DATABASE 
  2> RENAME FILE '/u01/oradata/mydb/datafile/o1_mf_tbs01_ziw3bopb_.dbf'
  3> TO '/u01/oradata/mydb/tbs0101.dbf';

SQL> ALTER DATABASE 
  2> DROP LOGFILE '/u01/oradata/mydb/onlinelog/o1_mf_1_wo94n2xi_.log';

SQL> ALTER TABLE emp 
  2> ALLOCATE EXTENT
  3> (DATAFILE '/u01/oradata/mydb/datafile/o1_mf_tbs1_2ixfh90q_.dbf');

You can backup and restore Oracle managed datafiles, tempfiles, and control files as you would corresponding non Oracle Managed Files. Using database-generated filenames does not impact the use of logical backup files such as export files. This is particularly important for tablespace point-in-time recovery (TSPITR) and transportable tablespace export files.

There are some cases where Oracle Managed Files behave differently. These are discussed in the sections that follow.

Dropping Datafiles and Tempfiles

Unlike files that are not managed by the database, when an Oracle managed datafile or tempfile is dropped, the filename is removed from the control file and the file is automatically deleted from the file system. The statements that delete Oracle Managed Files when they are dropped are:

DROP TABLESPACE
ALTER DATABASE TEMPFILE ... DROP

You can also use these statements, which always delete files, Oracle managed or not:

ALTER TABLESPACE ... DROP DATAFILE
ALTER TABLESPACE ... DROP TEMPFILE

Dropping Redo Log Files

When an Oracle managed redo log file is dropped its Oracle Managed Files are deleted. You specify the group or members to be dropped. The following statements drop and delete redo log files:

ALTER DATABASE DROP LOGFILE
ALTER DATABASE DROP LOGFILE MEMBER

Renaming Files

The following statements are used to rename files:

ALTER DATABASE RENAME FILE
ALTER TABLESPACE ... RENAME DATAFILE

These statements do not actually rename the files on the operating system, but rather, the names in the control file are changed. If the old file is an Oracle managed file and it exists, then it is deleted. You must specify each filename using the conventions for filenames on your operating system when you issue this statement.

Managing Standby Databases

The datafiles, control files, and redo log files in a standby database can be managed by the database. This is independent of whether Oracle Managed Files are used on the primary database.

When recovery of a standby database encounters redo for the creation of a datafile, if the datafile is an Oracle managed file, then the recovery process creates an empty file in the local default file system location. This allows the redo for the new file to be applied immediately without any human intervention.

When recovery of a standby database encounters redo for the deletion of a tablespace, it deletes any Oracle managed datafiles in the local file system. Note that this is independent of the INCLUDING DATAFILES option issued at the primary database.