Query for Database Schema Size

select OWNER,round (sum(bytes/1024/1024/1024)) "SIZE_IN_GB" from dba_segments
group by owner
order by SIZE_IN_GB desc;

Recovery Manager Commands

Command	Purpose
@ (at sign)	Run a command file.
@@ (double at sign)	Run a command file in the same directory as another command file that is currently running. The @@ command differs from the @command only when run from within a command file.
ADVISE FAILURE	Display repair options.
ALLOCATE CHANNEL	Establish a channel, which is a connection between RMAN and a database instance.
ALLOCATE CHANNEL FOR MAINTENANCE	Allocate a channel in preparation for issuing maintenance commands such as DELETE.
BACKUP	Back up database files, copies of database files, archived logs, or backup sets.
CATALOG	Add information about file copies and user-managed backups to the repository.
CHANGE	Mark a backup piece, image copy, or archived redo log as having the status UNAVAILABLE or AVAILABLE; remove the repository record for a backup or copy; override the retention policy for a backup or copy; update the recovery catalog with theDB_UNIQUE_NAME for the target database.
CONFIGURE	Configure persistent RMAN settings. These settings apply to all RMAN sessions until explicitly changed or disabled.
CONNECT	Establish a connection between RMAN and a target, auxiliary, or recovery catalog database.
CONVERT	Convert data file formats for transporting tablespaces and databases across platforms.
CREATE CATALOG	Create the schema for the recovery catalog.
CREATE SCRIPT	Create a stored script and store it in the recovery catalog.
CROSSCHECK	Determine whether files managed by RMAN, such as archived logs, data file copies, and backup pieces, still exist on disk or tape.
DELETE	Delete backups and copies, remove references to them from the recovery catalog, and update their control file records to statusDELETED.
DELETE SCRIPT	Delete a stored script from the recovery catalog.
DESCRIBE	List the column definitions of a table or view.
DROP CATALOG	Remove the schema from the recovery catalog.
DROP DATABASE	Delete the target database from disk and unregisters it.
DUPLICATE	Use backups of the target database to create a duplicate database that you can use for testing purposes or to create a standby database.
EXECUTE SCRIPT	Run an RMAN stored script.
EXIT	Quit the RMAN executable.
FLASHBACK DATABASE	Return the database to its state at a previous time or SCN.
GRANT	Grant privileges to a recovery catalog user.
HOST	Invoke an operating system command-line subshell from within RMAN or run a specific operating system command.
IMPORT CATALOG	Imports the metadata from one recovery catalog into a different recovery catalog.
LIST	Produce a detailed listing of backup sets or copies.
PRINT SCRIPT	Display a stored script.
QUIT	Exit the RMAN executable.
RECOVER	Apply redo log files and incremental backups to data files or data blocks restored from backup or data file copies, to update them to a specified time.
REGISTER DATABASE	Register the target database in the recovery catalog.
RELEASE CHANNEL	Release a channel that was allocated with an ALLOCATE CHANNELcommand or ALLOCATE CHANNEL FOR MAINTENANCE command.
REPAIR FAILURE	Repair one or more failures recorded in the automated diagnostic repository.
REPLACE SCRIPT	Replace an existing script stored in the recovery catalog. If the script does not exist, then REPLACE SCRIPT creates it.
REPORT	Perform detailed analyses of the content of the recovery catalog.
RESET DATABASE	Inform RMAN that the SQL statement ALTER DATABASE OPEN RESETLOGS has been executed and that a new incarnation of the target database has been created, or reset the target database to a prior incarnation.
RESTORE	Restore files from backup sets or from disk copies to the default or a new location.
RESYNC CATALOG	Perform a full resynchronization, which creates a snapshot control file and then copies any new or changed information from that snapshot control file to the recovery catalog.
REVOKE	Revoke privileges from a recovery catalog user.
RMAN	Start RMAN from the operating system command line.
RUN	Execute a sequence of one or more RMAN commands, which are one or more statements executed within the braces of RUN.
SEND	Send a vendor-specific quoted string to one or more specific channels.
SET	Set the value of various attributes that affect RMAN behavior for the duration of a RUN block or a session.
SHOW	Display the current CONFIGURE settings.
SHUTDOWN	Shut down the target database. This command is equivalent to the SQL*Plus SHUTDOWN command.
SPOOL	Write RMAN output to a log file.
SQL	Execute a SQL statement or PL/SQL procedures from within Recovery Manager.
SQL (Quoted)	Execute a SQL statement from within Recovery Manager. See the SQL command for improved syntax.
STARTUP	Start the target database. This command is equivalent to the SQL*Plus STARTUP command.
SWITCH	Specify that a data file copy is now the current data file, that is, the data file pointed to by the control file. This command is equivalent to the SQL statement ALTER DATABASE RENAME FILE as it applies to data files.
TRANSPORT TABLESPACE	Create transportable tablespace sets from backup for one or more tablespaces.
UNREGISTER	Unregister a database from the recovery catalog.
UPGRADE CATALOG	Upgrade the recovery catalog schema from an older version to the version required by the RMAN executable.
VALIDATE	Examine a backup set and report whether its data is intact. RMAN scans all of the backup pieces in the specified backup sets and looks at the checksums to verify that the contents can be successfully restored.