String 

PARALLEL_INSTANCE_GROUP = group_name 

Dynamic. Scope = ALTER SESSION, ALTER SYSTEM. 

A group consisting of all instances currently active 

Any group name specified in the INSTANCE_GROUPS parameter of any active instance 

Different instances can have different values. 

PARALLEL_INSTANCE_GROUP is an Oracle Parallel Server parameter that you can specify in parallel mode only. Used in conjunction with the INSTANCE_GROUPS parameter, it lets you restrict parallel query operations to a limited number of instances. See "INSTANCE_GROUPS".  

This parameter identifies the parallel instance group Oracle will use for spawning parallel execution processes. Parallel operations will spawn parallel execution processes only on instances that specify a matching group in their INSTANCE_GROUPS parameter.  

If the value of PARALLEL_INSTANCE_GROUP does not correspond to an instance group name specified for an active instance, Oracle returns an error.

See Also: Oracle8i Parallel Server Administration, Deployment, and Performance for more information on parallel query execution in an Oracle Parallel Server environment.