ALTER DATABASE

Purpose

Use the ALTER DATABASE command to mount or open a database.

See Also:

Oracle Database SQL Language Reference for ALTER DATABASE syntax and semantics

Syntax

alterDatabase::=

Description of the illustration alterdatabase.gif

Prerequisites

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

Semantics

Syntax Element	Description
`MOUNT`	Mounts the database without opening it. Issuing the command with this option is equivalent to the SQL statement `ALTER` `DATABASE` `MOUNT`.
`OPEN`	Opens the database (see Example 2-13). When you open the database after `RECOVER` `DATABASE`, RMAN re-creates any locally managed tempfiles recorded in the RMAN repository if necessary. However, if you perform recovery with a backup control file and no recovery catalog, then RMAN does not record tempfiles created after the control file backup in the RMAN repository. Also, RMAN does not re-create the tempfiles automatically.
`RESETLOGS`	Archives the current online redo logs (or up to the last redo record before redo corruption if corruption is found), clears the contents of the online redo logs, and resets the online redo logs to log sequence 1. The RMAN command `ALTER DATABASE OPEN RESETLOGS` is equivalent to the SQL statement `ALTER` `DATABASE` `OPEN` `RESETLOGS`. If you use a recovery catalog, then RMAN issues 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` rather than the RMAN command of the same name, then you must manually run the `RESET` `DATABASE` command.

Examples

Example 2-13 Making a Consistent Database Backup

Assume that the database is open and you want to make a consistent backup of the whole database. This example shuts down the database consistently, mounts the database, makes a consistent whole database backup, and then opens the database.

SHUTDOWN IMMEDIATE;
STARTUP MOUNT;
BACKUP DATABASE PLUS ARCHIVELOG;
# Now that the backup is complete, open the database.
ALTER DATABASE OPEN;

Example 2-14 Mounting the Database After Restoring the Control File

This example restores the control file, mounts it, and performs recovery. Finally, the example resets the online redo logs.

STARTUP FORCE NOMOUNT;
RESTORE CONTROLFILE FROM AUTOBACKUP;
ALTER DATABASE MOUNT;
# you must run the RECOVER command after restoring a control file even if no datafiles 
# require recovery
RECOVER DEVICE TYPE DISK DATABASE;
ALTER DATABASE OPEN RESETLOGS;