instance_stickiness
This attribute should only be used for a database running in RAC mode. By default, it is set to TRUE. If you set instance_stickiness to TRUE, jobs start running on the instance with the lightest load and the Scheduler thereafter attempts to run on the instance that it last ran on. If that instance is either down or so overloaded that it will not start new jobs for a significant period of time, another instance will run the job. If the interval between runs is large, instance_stickiness will be ignored an the job will be handled as if it were a non-sticky job.
这个属性在RAC中使用，默认是true， 是true时，会在负载轻的、上一次运行的节点上运行。 如果这个节点down了或负载太重不能建新的job，那么会在另外的节点上运行。如果job运行间隔时间很长，这个值会被忽略