IS 432: DATABASE ADMINISTRATION

Lecture 4: Parameter Files.Information Systems Department

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Parameter Files

A parameter file is a file that contains a list of initialization parameters and a value for each parameter. Parameter file is read when instance

start. This file must at a minimum specify the

DB_NAME parameter. All other parameters have default

values.

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Parameter Files

There are two types of parameter files:

1-Server parameter file(SPFILE).

2-Text initialization parameter file(PFILE).

To know what type of file your instance

running (SQL Commands):

SHOW PARAMETER SPFILE

Or SHOW PARAMETER PFILE

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Show parameter spfile & pfile

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Initialization Parameters

Initialization parameters perform functions, such as:

Set limits for the entire database; e.g. specify names of files or directories required by the database.

Set user or process limits; e.g. the maximum number of database users.

Set limits on database resources; e.g. the amount of space initially allocated for each memory area.

Optimize performance; e.g. adjusting memory structures, such as the number of database

buffers in memory.

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Initialization Parameters: Examples

Parameter Specifies

CONTROL_FILES One or more control file names with paths.

DB_BLOCK_SIZE Standard database block size used by all table spaces

PROCESSESMaximum number of OS user processes and background processes that can simultaneously connect

DB_CACHE_SIZE Size of the standard block buffer cache

DB_FILE_MULTIBLOCK_READ_COUNT

Maximum number of blocks read during an input/output (I/O) operation.

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Initialization Parameters: Examples

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Viewing and Modifying Initialization Parameters

You can change the value of a parameter in a parameter file in one of the following ways:

o By editing an initialization parameter file using (EM).

o By issuing an ALTER SYSTEM SET ... using (SQL*).

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Viewing and Modifying Initialization Parameters by SQL plus

Viewing Parameters :Show parameters

Modifying Parameters :ALTER SYSTEM SET PARAMETER_NAME = NEW VALUE SCOPE = MEMORY OR SCOPE= BOTH OR SCOPE = SPFILE;

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Viewing and Modifying Initialization Parameters

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Viewing and Modifying Initialization Parameters

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Viewing and Modifying Initialization Parameters

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Viewing and Modifying Initialization Parameters

You can modify the initialization parameters for the database in one of three ways:

1- Until the instance is shut down: The new values for the initialization parameters are applied to the currently running instance, but, when the database is restarted, the initialization parameter values revert to their previous settings. SCOOP= MEMORY.

A- On the Current subpage, in the Value column, enter new values for the initialization parameters.B-Ensure that Apply changes in current running instance(s) mode to SPFile is not selected.

C- Click Apply. A confirmation message appears.

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Viewing and Modifying Initialization Parameters

2- From now until the initialization parameter is changed again: The changes are applied to the currently running instance and are also stored in the server parameter file. The changes made to the initialization parameters persist when the database is restarted. SCOOP=BOTH.

A- On the Current subpage, in the Value column, enter new values for the initialization parameters.B- Select Apply changes in current running instance(s) mode to SPFile.C- Click Apply. A confirmation message appears.

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Viewing and Modifying Initialization Parameters

3- When the database is restarted: The new values for the initialization parameters are recorded in server parameter file, but are not applied to the currently running instance. The changes take effect only when the database is restarted. SCOOP=SPFILE.

A- Click SPFile to view the SPFile subpage.B- In the Value column, enter new values for the initialization parameters.C- Click Apply. A confirmation message appears.