With the Resource Manager, you can: A resource consumer group (consumer group) is a collection of user sessions that are grouped together based on their processing needs.When a session is created, it is automatically mapped to a consumer group based on mapping rules that you set up.However, only one resource plan is active at a time.
A directive has several ways in which it can limit resource allocation for a consumer group.
For example, it can control how much CPU the consumer group gets as a percentage of total CPU, and it can limit the total number of sessions that can be active in the consumer group.
The initial consumer group of a session is determined by the mapping rules that you configure.
For information on how to configure mapping rules, see "Specifying Session-to–Consumer Group Mapping Rules".
In an environment with multiple concurrent user sessions that run jobs with differing priorities, all sessions should not be treated equally.
The Resource Manager enables you to classify sessions into groups based on session attributes, and to then allocate resources to those groups in a way that optimizes hardware utilization for your application environment.
As a database administrator (DBA), you can manually switch a session to a different consumer group.
Similarly, an application can run a PL/SQL package procedure that switches its session to a particular consumer group.
If the CPU usage is below 100%, the database is not CPU-bound and hence there is no need to enforce allocations to ensure that all sessions get their designated resource allocation.
In addition, when allocations are enforced, unused allocation by any consumer group can be used by other consumer groups.
Each subplan allocates its portion of the total resource allocation among its consumer groups and subplans.