## Database Parameters

### Definition

Database parameters define fundamental properties of the database instance.

The following types of database parameters exist:

● General Database Parameters

● Special Database Parameters

● Support Database Parameters

● liveCache Database Parameters (for SAP liveCache database instances only)

Database parameters have a range of properties (see Properties of Database Parameters).

#### Default Parameter File

The default parameter file cserv.pcf (see Configuration Files) contains the default values, value ranges, calculation formulas and properties of the database parameters. The default parameter file and a database parameter file (initially filled with the default values) are installed with the database instance. When a user changes a database parameter, the database system saves the new value for the database parameter in the database parameter file.

### Use

When creating a new database instance, you can use the system default for the database parameters, copy the database parameters from a different database instance, or else import the database parameter file from a complete data backup. You can change the values of most database parameters later.

Changes to database parameters do not take effect until the database instance is restarted.

You can also change some database parameters while the database is running (see description of individual database parameters). In addition you can choose how long the change is to be effective for these database parameters:

■ Until the next restart

■ Not until after the next restart

■ Immediately and permanently

The database system saves the values of the database parameters in binary format in the database parameter file of the database instance. To display or change the database parameters, use the Database Manager or, in SAP systems, the CCMS:

● Database Manager GUI, Displaying and Changing Database Parameters

● Database Manager CLI, param_put

● Database Administration Tutorial, Changing the Values of Database Parameters

● Database Administration in CCMS: MaxDB, Parameters

● Database Administration in CCMS: SAP liveCache Technology, Configuring Parameters

You can also use these tools to display the history of the values of the database parameters.

See also:

Creating and Configuring a Database Instance