In this Document

Applies to:

Purpose

This document describes how to find and change the "db_name" for a database, or the ORACLE_SID for an instance, without recreating the database.

This Note is not intented for cloning from existing database, That will be covered in the Note 562556.1

Scope

For DBAs requiring to either find or change the db_name or ORACLE_SID.

Details

Find the current DB_NAME and ORACLE_SID:

Query the views v$database and v$thread.

V$DATABASE gives DB_NAME
V$THREAD gives ORACLE_SID

If ORACLE_SID = DB_SID and db_name = DBNAME:

To find the current value of ORACLE_SID:
(For Oracle9i/Oracle10g, must use SQL*Plus)

SVRMGR> select instance from v$thread;

INSTANCE
----------------
DB_SID

To find the current value of DB_NAME:

SVRMGR> select name from v$database;

NAME
---------
DBNAME

Modify a database to run under a new ORACLE_SID:

1. Shutdown the instance

The database must be shutdown with SHUTDOWN NORMAL or SHUTDOWN IMMEDIATE.
It must not be shutdown abnormally using SHUTDOWN ABORT.

2. Backup all control, redo, and data files.

3. Go through the environment settings and redefine the ORACLE_SID environment variable to a new value.
For Unix, you can check for instance .profile, .cshrc, .login, oratab.
On Unix, you can also search through disks and do a grep ORACLE_SID *
For Windows use the 'set' command in a command window and make corrections via the System Control Panel applet (Advanced tab > Environment Variables).
For all Operating systems, check the tnsnames.ora.

4. Change locations to the "dbs" directory (or "database" directory for Windows)

$ cd $ORACLE_HOME/dbs

and rename the following files:

• init.ora (or use pfile to point to the init file)
• control file(s). This is optional if you do not rename any of the controlfiles, and the control_files parameter is used. The "control_files" parameter is set in the "init.ora" file or in a file it references with the ifile parameter. Make sure that the control_file parameter does not point to old file names, if they have been renamed.
• "crdb.sql" & "crdb2.sql", This is optional, these are only used at database creation.

NOTE: for Oracle9i and higher, if using an SPFILE: You must rename it (i.e. spfile.ora) along with changing parameter values in the SPFILE. Please review the following
for more information on SPFILE.
Note 162491.1 Spfile and Init.ora Parameter File Startup of an Oracle9i Instance
Note 137483.1 How to Modify the Content of an SPFILE Parameter File

5. To rename the database files and redo log files, follow the instructions in Note 9560.1.

6. Change the ORACLE_SID environment variable to the new value.

7. Check in the "$ORACLE_HOME/dbs" directory to see if the password file has been enabled. If enabled, the file "orapw" will exist and a new password file for the new SID must be created (renaming the old file will not work). If "orapw" does not exist, skip to step 8. To create a new password file, issue the following command as oracle owner:

orapwd file=orapw password=?? entries=granted permission to start the database instance>

8. Start up the database and verify that it works. Once this is done, shutdown the database and take a final backup of all control, redo, and data files.

The database must be shutdown with SHUTDOWN NORMAL or SHUTDOWN IMMEDIATE.
It must not be shutdown abnormally using SHUTDOWN ABORT.

9. When the instance is started, the control file is updated with the current ORACLE_SID.

Change the "db_name" for a Database

1. Login to Server Manager (Oracle7 through Oracle8i)/ SQL*Plus for Oracle9i/Oracle10g

% svrmgrl
SVRMGR> connect internal

NOTE: For Oracle9i/Oracle10g, must use SQL*Plus (svrmgrl is obsolete after Oracle8i)
% sqlplus "/ as sysdba"

2. Type

SVRMGR> alter system switch logfile;

to force a checkpoint.

3. Type

SVRMGR> alter database backup controlfile to trace resetlogs;

This will create a trace file containing the "CREATE CONTROLFILE" command to recreate the controlfile in its current form.

4. Shutdown the database and exit SVRMGR

SVRMGR> shutdown

SVRMGR> exit

The database must be shutdown with SHUTDOWN NORMAL or SHUTDOWN IMMEDIATE.
It must not be shutdown abnormally using SHUTDOWN ABORT.

5. Change locations to the directory where the trace files are located. They are usually in the "$ORACLE_HOME/rdbms/log" directory. If "user_dump_dest" is set in the "init.ora" file, then go to the directory listed in the "user_dump_dest" variable. The trace file will have the form. "ora_NNNN.trc with NNNN being a number.

NOTE: for Oracle9i/Oracle10g if using an SPFILE: Please review the following for changing parameter values in the SPFILE. Note 137483.1 How to Modify the Content of an SPFILE Parameter File

6. Copy the contents of the trace file starting from the line with STARTUP NOMOUNT down to the end of the trace file and put it in a new file called something like "ccf.sql".

7. Edit the "ccf.sql" file

FROM: CREATE CONTROLFILE REUSE DATABASE "olddbname" RESETLOGS ...
TO: CREATE CONTROLFILE set DATABASE "newdbname" RESETLOGS ...

Change the word 'REUSE' to 'set' and the 'olddbname' to 'newdbname'.

It is possible to recreate the controlfile using the syntax:
CREATE CONTROLFILE REUSE set DATABASE "newdbname" RESETLOGS ...

But this syntax will allow the existing controlfiles to be overwritten without giving an error.

FROM:
# Recovery is required if any of the datafiles are restored backups,
# or if the last shutdown was not normal or immediate.
RECOVER DATABASE USING BACKUP CONTROLFILE
TO:
# Recovery is required if any of the datafiles are restored backups,
# or if the last shutdown was not normal or immediate.
# RECOVER DATABASE USING BACKUP CONTROLFILE

The last command in ccf.sql should be:
alter database open resetlogs

NOTE : In cases of Oracle 9i, the script. must to be modified and #(as comments) changed to -- as "#" is not recognized as a comment in SQL*Plus

8. Save and exit the "ccf.sql" file

9. Rename the old control files for backup purposes and so that they do not exist when creating the new ones.

10. Edit the "init.ora" file so that db_name="newdb_name" .

NOTE: for Oracle9i/Oracle10g if using an SPFILE: Please review the following for changing parameter values in the SPFILE.
Note 137483.1 How to Modify the Content of an SPFILE Parameter File

11. Login to Server Manager

% svrmgrl
SVRMGR> connect internal

NOTE: For Oracle9i/Oracle10g, must use SQL*Plus (svrmgrl is obsolete after Oracle8i)
% sqlplus "/ as sysdba"

12. Run the "ccf.sql" script.

SVRMGR> @ccf

This will issue a startup nomount, and then recreate the controlfile.

If, at this point, an error stating that a file needs media recovery is reported, then the database was not shutdown normally as specified in step 4. Try recovering the database using the redo in the current logfile, by issuing:

SVRMGRL> recover database using backup controlfile until cancel;

This will prompt for an archived redologfile. It may be possible to open the database after applying the current logfile. BUT this is not guaranteed.

To apply the necessary redo, check the online logfiles and apply the one with the same sequence number as reported in the message. This usually is the logfile with status=CURRENT. If not apply, the logfiles in turn until the logfile with status=CURRENT has been applied. If, after applying the current logfile, the database will not open then it is highly likely that the operation must be restarted having shutdown the database normally.

To find a list of the online logfiles:

SVRMGR> select group#, seq#, status from v$log;
GROUP# SEQUENCE# STATUS
---------- --------- ----------------
1 123 CURRENT <== this redo needs to be applied
2 124 INACTIVE
3 125 INACTIVE
4 126 INACTIVE
5 127 INACTIVE
6 128 INACTIVE
7 129 INACTIVE

7 rows selected.

SVRMGR> select member
from v$logfile
where GROUP# = 1;

Member
------------------------------------
/u02/oradata/V815/redoV81501.log

After applying the current online log file the following prompt should be displayed:

Log Applied
Media Recovery Complete

At this point the database can be opened with:

SVRMGR> alter database open resetlogs;

13. After the 'alter database open (resetlogs)' command in the controlfile create script, there are commands to add the necessary temp files.

Next example is from 11.2:

...
ALTER DATABASE OPEN RESETLOGS;
-- Commands to add tempfiles to temporary tablespaces.
-- Online tempfiles have complete space information.
-- Other tempfiles may require adjustment.
ALTER TABLESPACE TEMP ADD TEMPFILE '+DATA/v1120/tempfile/temp.271.786464435'
SIZE 288358400 REUSE AUTOEXTEND ON NEXT 655360 MAXSIZE 32767M;
-- End of tempfile additions.

Please make sure, the required temp files are indeed added.

14. The global database name may also need to be changed:

alter database rename global_name to .

See Note 1018634.102 for further detail.

15. Make sure the database is working.

16. Shutdown and backup the database.

The database must be shutdown with SHUTDOWN NORMAL or SHUTDOWN IMMEDIATE.
It must not be shutdown abnormally using SHUTDOWN ABORT.

References