PARALLEL_INSTANCE_GROUP

Property	Description
Parameter type	String
Syntax	`PARALLEL_INSTANCE_GROUP =` `service_name` `\|` `group_name`
Default value	There is no default value; parallel execution is enabled across all currently active instances.
Modifiable	`ALTER SESSION`, `ALTER SYSTEM`
Range of values	Any service name or any group name specified in the `INSTANCE_GROUPS` parameter of any active instance
Oracle RAC	Multiple instances can have different values.

PARALLEL_INSTANCE_GROUP is an Oracle RAC parameter that you can specify in parallel mode only. Used in conjunction with services or with the INSTANCE_GROUPS parameter, it lets you restrict parallel query operations to a limited number of instances. Note that the INSTANCE_GROUPS parameter has been deprecated.

This parameter identifies the parallel instance group Oracle will use for spawning parallel execution processes. If used in conjunction with services, then parallel operations will spawn parallel execution processes only on instances defined in the service. If used in conjunction with INSTANCE_GROUPS, then parallel operations will spawn parallel execution processes only on instances that specify a matching group in their INSTANCE_GROUPS parameter.

If the value assigned to PARALLEL_INSTANCE_GROUP is the name of a service or group that does not exist, then the operation runs serially. No parallelism is used.