n is either 1 or 0. The default value is 1.
When IdKey is enabled (n = 1), when a Primary Key constraint is specified through DDL it does not also become the IDKey index in the class definition.
When this parameter is not enabled, a Primary Key constraint specified through DDL also becomes the IDKey index in the class definition. This ption generally gives better performance, but means that the Primary Key fields cannot be updated.
Changing This Parameter
On the SQL page of the Management Portal (System Administration > Configuration > SQL and Object Settings > SQL), select Define primary key as ID key for tables created via DDL to disable IdKey.
To set the desired value for IdKey from the Terminal, use the SetOption(“DDLPKeyNotIDKey”) method of the %SYSTEM.SQL.Util class. See the class reference for details.
You can also change IdKey with the Config.SQL class (as described in the class reference) or by editing the CPF in a text editor (as described in the Editing the Active CPF section of the “Introduction to the Configuration Parameter File” chapter in this book).