ALTER DATABASE

Syntax

Text description of the illustration alterDatabase.gif

Purpose

To mount or open a database.

Restrictions and Usage Notes

• Execute this command either within the braces of a RUN command or at the RMAN prompt.
• The target instance must be started.

Keywords and Parameters

Syntax Element	Description
MOUNT	Mounts the database without opening it. This option is equivalent to the SQL statement ALTER DATABASE MOUNT.
OPEN	Opens the database.
RESETLOGS	Resets the online redo logs to log sequence 1. The RMAN RESETLOGS option is equivalent to the SQL statement ALTER DATABASE OPEN RESETLOGS. If you use a recovery catalog, then RMAN performs an implicit RESET DATABASE after the database is opened to make this new incarnation the current one in the catalog. If you execute the SQL statement ALTER DATABASE OPEN RESETLOGS (not the RMAN command of the same name), then you must manually run the RESET DATABASE command.

Examples

Opening the Database After a Backup: Example

This example mounts the database, takes a whole database backup, then opens the database. At the RMAN prompt enter:

STARTUP MOUNT; 
BACKUP DATABASE;  
# now that the backup is complete, open the database. 
ALTER DATABASE OPEN; 

Mounting the Database After Restoring the Control File: Example

To restore the control file to its default location when connected to a recovery catalog, enter the following:

STARTUP NOMOUNT;
RESTORE CONTROLFILE;
ALTER DATABASE MOUNT;
# you must run the RECOVER command after restoring a control file even if no datafiles 
# require recovery
RECOVER DATABASE;
ALTER DATABASE OPEN RESETLOGS;
# if the database uses locally-managed temporary tablespaces, then you must add tempfiles
# to these tablespaces after restoring a backup control file
SQL " ALTER TABLESPACE temp ADD TEMPFILE ''?/oradata/trgt/temp01.dbf'' REUSE";

Performing RESETLOGS After Incomplete Recovery: Example

This example uses a manually allocated channel to perform incomplete recovery and then resets the online redo logs:

RUN
{
  ALLOCATE CHANNEL ch1 DEVICE TYPE sbt; 
  SET UNTIL SCN 1024;
  RESTORE DATABASE; 
  RECOVER DATABASE;
  ALTER DATABASE OPEN RESETLOGS;
}