Since Oracle 9i, Oracle has introduced the use of SPFILE over INIT files for control of the RDBMS initialization parameters. The introduction of SPFILE was to allow for the dynamic changing of initialization parameters setting while the database is up and eliminating the need to open an OS layer file to make changes to the ORACLE initialization parameters. This article will cover: how to change initialization parameter from within an Oracle database. This procedure is the same on any OS.

1. Logon to your Oracle database server as the Oracle software owner.

2. Connect to SQLPLUS with SYSDBA privileges.

mylinux :> sqlplus ‘/ as SYSDBA’

SQL*Plus: Release 10.2.0.4.0 – Production on Sun Sep 27 09:49:04 2009

Copyright (c) 1982, 2007, Oracle. All Rights Reserved.

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 – 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL>

3. We use the alter system command to change initialization parameters from within the Oracle database while an SPFILE is in use. The following is an example of the alter system command.

alter system set {initialization_parameter} = {new_value} scope = {scope}

4. The key here is the scope clause which can have three possible values:

MEMORY – No changes are made to the SPFILE at all and the change is only mode in the current instance. To use this option, the initialization parameter must be dynamic and modifiable.

BOTH – Changes are made both in the current instance and in the SPFILE for future restart of the database. To use this option, the initialization parameter must be dynamic and modifiable.

SPFILE – Changes are not made in the current instance and the SPFILE is updated with new initialization parameter setting; however it will only take affect on restart of the database.

5. Examples of changing initialization parameter with alter system command:

SQL> alter system set user_dump_dest = ‘/opt/oracle/udump’ scope=both;

System altered.

SQL> alter system set user_dump_dest = ‘/opt/oracle/udump ‘ scope=memory;

System altered.

SQL> alter system set audit_file_dest=’/opt/oracle/udump ‘ scope=spfile;

System altered.

This completes adjusting initialization parameters in an SPFILE.

Larry J. Catt, OCP 9i, 10g
oracle@allcompute.com
www.allcompute.com