IS 432: DATABASE ADMINISTRATION Lecture 4: Parameter Files. Information Systems Department 1

Parameter Files Information Systems Department 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. 2

Parameter Files Information Systems Department 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 3

Show parameter spfile & pfile Information Systems Department 4

Initialization Parameters Information Systems Department 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. 5

Initialization Parameters: Examples Information Systems Department 6 Parameter Specifies CONTROL_FILESOne or more control file names with paths. DB_BLOCK_SIZEStandard database block size used by all table spaces PROCESSES Maximum number of OS user processes and background processes that can simultaneously connect DB_CACHE_SIZESize of the standard block buffer cache DB_FILE_MULTIBLOCK_READ_COUNT Maximum number of blocks read during an input/output (I/O) operation.

Initialization Parameters: Examples Information Systems Department 7

Viewing and Modifying Initialization Parameters Information Systems Department 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*). 8

Viewing and Modifying Initialization Parameters by SQL plus Information Systems Department 9  Viewing Parameters : Show parameters Modifying Parameters : ALTER SYSTEM SET PARAMETER_NAME = NEW VALUE SCOPE = MEMORY OR SCOPE= BOTH OR SCOPE = SPFILE;

Viewing and Modifying Initialization Parameters Information Systems Department 10

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Viewing and Modifying Initialization Parameters Information Systems Department 13 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.

Viewing and Modifying Initialization Parameters Information Systems Department 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.

Viewing and Modifying Initialization Parameters Information Systems Department 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.