Autonomous Data Warehouse comes with predefined CPU/IO shares assigned to different consumer groups. You can modify these predefined CPU/IO shares if your workload requires different CPU/IO resource allocations.
By default, the CPU/IO shares assigned to the consumer groups HIGH, MEDIUM, LOW are 4, 2, and 1, respectively. The shares determine how much CPU/IO resources a consumer group can use with respect to the other consumer groups. With the default settings the consumer group HIGH will be able to use 4 times more CPU/IO resources compared to LOW and 2 times more CPU/IO resources compared to MEDIUM, when needed. The consumer group MEDIUM will be able to use 2 times more CPU/IO resources compared to LOW, when needed.
You can set CPU/IO shares from the service console or using the PL/SQL package
Follow these steps to set CPU/IO shares from the service console:
- From the Autonomous Data Warehouse details page, click Service Console.
- On the Service Console click Administration.
- Click Set Resource Management Rules.
- Select CPU/IO shares to set CPU/IO share values for consumer groups.
- Set the CPU/IO share values.
- Click Save changes.
For example, the following figure shows CPU/IO share values that you can modify:
Description of the illustration dwcs_manage_set_shares.png
Click Load Default Values to load the default values; then click Save changes to apply the populated values.
You can also change the default values using the PL/SQL procedure
For example, running the following script with the ADMIN user sets CPU/IO shares to 8, 2, and 1 for consumer groups HIGH, MEDIUM, and LOW respectively. This will allow the consumer group HIGH to use 4 times more CPU/IO resources compared to the consumer group MEDIUM and 8 times CPU/IO resources compared to the consumer group LOW:
BEGIN cs_resource_manager.update_plan_directive(consumer_group => 'HIGH', shares => 8); cs_resource_manager.update_plan_directive(consumer_group => 'MEDIUM', shares => 2); cs_resource_manager.update_plan_directive(consumer_group => 'LOW', shares => 1); END; /