kinds of parameters:

--- Explicit: Having an entry in the file

--- Implicit: No entry within the file, but assuming the Oracle default values

types of initialization parameter file:

--- Static parameter file, PFILE,commonly referred to as initSID.ora

--- Persistent parameter file, SPFILE,commonly referred to as spfileSID.ora

Parameter File Contents

--- A list of instance parameters

--- The name of the database the instance is associated with

--- Allocations for memory structures of the System Global Area (SGA)

--- What to do with filled online redo log files

--- The names and locations of control files

--- Information on undo segments

PFILE : initSID.ora

--- a text file that can be modified with an operating system editor.

--- Modifications to the file are made manually.

--- Changes to the file take effect on the next startup.

--- Its default location is $ORACLE_HOME/dbs.

Rules for Specifying Parameters in PFILE:

--- Specify the values in the following format: keyword=value.

--- All parameters are optional.

--- Parameters can be specified in any order.

--- Comment lines begin with the # symbol.

--- Multiple values are enclosed in parentheses and separated by commas.

--- Enclose parameters in double quotation marks to include character literals.

--- Additional files can be included with the keyword IFILE.

--- If case is significant for the operating system, then it is also significant in filenames.

--- The server has a default value for each parameter. This value may be operating system dependent, depending on the parameter.

SPFILE : spfileSID.ora:

--- Binary file with the ability to make changes persistent across shutdown and startup

--- Maintained by the Oracle server

--- Records parameter value changes made with the ALTER SYSTEM command

--- Can specify whether the change being made is temporary or persistent

--- Values can be deleted or reset to allow an instance to revert to the default value

eg:ALTER SYSTEM SET undo_tablespace = 'UNDO2';

Change parameter in spfile

Syntax:ALTER SYSTEM SET parameter=value ;

Create a spfile:

Syntax:CREATE SPFILE [='SPFILE---NAME'] FROM PFILE[='PFILE---NAME']

Where:

--- SPFILE---NAME: Name of the SPFILE to be created: if not specified, the default SPFILE name is assumed.

--- PFILE---NAME: Name of a PFILE, must be available on the server side.

The CREATE SPFILE command requires the SYSDBA role to execute.

Create a pfile:

Syntax:CREATE PFILE [='PFILE---NAME'] FROM SPFILE[='SPFILE---NAME']

The CREATE PFILE command requires the SYSDBA role to execute.