| Property | Description |
|---|---|
| Parameter type | Boolean |
| Default value | false |
| Modifiable | ALTER SESSION, ALTER SYSTEM |
| Range of values | true | false |
| Basic | No |
| Real Application Clusters | Multiple instances can have different values. |
PARALLEL_IO_CAP_ENABLED specifies whether or not Oracle caps the default degree of parallelism to no greater than what the I/O system can support. This new value is calculated based on the results of the resource manager's I/O calibration package.
If PARALLEL_IO_CAP_ENABLED is set to true and the database I/O capacity has been calibrated, then Oracle will reduce the default degree of parallelism if the I/O capacity cannot support the available number of CPUs. To calibrate the I/O capacity, use the DBMS_RESOURCE_MANAGER.CALIBRATE_IO procedure to measure the system's I/O capacity. Oracle then computes the degree of parallelism so as not to exceed the system's I/O capacity.
See Also:
Oracle Database Data Warehousing Guide for information on initializing and tuning parameters for parallel execution