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Initialization Parameters

Initialization parameters fall into various groups. Parameters perform the following

function:

Set limits for the entire database Set user or process limits

Set limits on database resources

Affect performance

Database Administrators can use initialization parameters to:

Optimize performance by adjusting memory structures, such as the number of

database buffers in memory

Set database limits, such as the maximum number of database users

Specify names of files or directories required by the database

Types of Initialization Parameters

The oracle server has following types of Initialization parameters:

Derived Parameters

Operating System-Dependent Parameters

Variable Parameters

Derived Parameters

Some initialization parameters are derived, meaning that their values are calculated

from the values of other parameters. Normally, you should not alter values for derived

parameters, but if you do, then the value you specify will override the calculated value.

For example, the default value of the SESSIONS parameter is derived from the value of

the PROCESSES parameter. If the value of PROCESSES change then the default

value of SESSIONS changes as well

Operating System-Dependent Parameters

The valid values or value ranges of some parameters depend upon the operating

system. For example, the parameters DB_BLOCK_BUFFERS indicates the number of

data buffers in main memory, and its maximum value depends on the operating system.

Variable Parameters

The variable initialization parameters offer the most potential for improving system

performance. Some variable parameters set capacity limits but do not affect

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performance. For example, when the value of OPEN_CURSORS is 10, a user process

attempting to open its eleventh cursor receives an error. Other variable parameters

affect performance but do not impose absolute limits. For example, reducing the value

of DB_BLOCK_BUFFERS does not prevent work even though it may slow down

performance.

Following is the list of some Basic Initialization Parameters:

CLUSTER DATABASE

CONTROL FILES

DB_BLOCK_SIZE

DB_DOMAIN

DB_NAME

INSTANCE_NUMBER

JOB_QUE_PROCESSES

OPEN_CURSORS

PROCESSES

SESSIONS

ROLLBACK SEGMENTS

UNDO TABLESPACE

CONTROL FILE

A control file is a small binary file that is part of an Oracle Database. The control file is

used to keep track of the databases status and physical structure.

Every oracle database must have at least one control file.

The control file contain following information:

Database name

Timestamp of database creation

Names and locations of Data files

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Names and locations of Redo log files

The current log sequence number

Checkpoint information

Without control file, the database cannot be mounted and recovery is difficult. The

control file of an Oracle Database is created at the same time as the database. Bydefault, at least one copy of the control file is created during database creation. on

Some operating systems the default is to create multiple copies.