Changing node and database configuration files

To update the database configuration file, run the AUTOCONFIGURE command with the appropriate options.

About this task

The Configuration Advisor helps you to tune performance and to balance memory requirements for a single database per instance by suggesting which configuration parameters to modify and providing suggested values for them.

If you plan to change any database partition groups (adding or deleting database partitions, or moving existing database partitions), the node configuration file must be updated. If you plan to change the database, review the values for the configuration parameters. You can adjust some values periodically as part of the ongoing changes made to the database that are based on how it is used.

Note: If you modify any parameters, the values are not updated until:

For database parameters, the first new connection to the database after all applications are disconnected
For database manager parameters, the next time that you stop and start the instance

In most cases, the values recommended by the Configuration Advisor provide better performance than the default values because they are based on information about your workload and your own particular server. However, the values are designed to improve the performance of, though not necessarily optimize, your database system. Think of the values as a starting point on which you can make further adjustments to obtain optimized performance.

In Version 9.1, the Configuration Advisor is automatically invoked when you create a database. To disable this feature, or to explicitly enable it, use the db2set command before creating the database. Examples:

   db2set DB2_ENABLE_AUTOCONFIG_DEFAULT=NO
   db2set DB2_ENABLE_AUTOCONFIG_DEFAULT=YES

See Automatic features for other features that are enabled by default.

Procedure

To change database or database manager configuration parameters:

Use the Configuration Advisor.
- From the command line, use the AUTOCONFIGURE command.
- From a client application, call the db2AutoConfig API.
From IBM® Data Studio, right-click the instance or database to open the task assistant to change the database manager or database configuration parameters.
From the command line, use the UPDATE DATABASE MANAGER CONFIGURATION and UPDATE DATABASE CONFIGURATION commands.
For example, to update individual parameters in the database manager configuration, enter:
```
   UPDATE DBM CFG USING config_keyword value
```
To update individual parameters in the database configuration, enter:
```
UPDATE DB CFG FOR database_alias
USING config_keyword value
```
You can update one or more config_keyword value combinations in a single command.

Most changes to the database manager configuration file become effective only after they are loaded into memory. For a server configuration parameter, this occurs during the running of the START DATABASE MANAGER command. For a client configuration parameter, this occurs when the application is restarted.
From a client application, call the db2CfgSet API.

What to do next

To view or print the current database manager configuration parameters, use the GET DATABASE MANAGER CONFIGURATION command.