TriggerAction implementations process events generated by triggers in order to ensure the cluster’s
health and good use of resources.
Currently two implementations are provided: ComputePlanAction and ExecutePlanAction.
Compute Plan Action
The ComputePlanAction uses the policy and preferences to calculate the optimal set of Collection API
commands which can re-balance the cluster in response to trigger events.
Currently, it has no configurable parameters.
Execute Plan Action
The ExecutePlanAction executes the Collection API commands emitted by the ComputePlanAction against
the cluster using SolrJ. It executes the commands serially, waiting for each of them to succeed before
continuing with the next one.
Currently, it has no configurable parameters.
If any one of the commands fail, then the complete chain of actions are
executed again at the next run of the trigger. If the Overseer node fails while ExecutePlanAction is running,
then the new Overseer node will run the chain of actions for the same event again after waiting for any
running Collection API operations belonging to the event to complete.
Please see SolrCloud Autoscaling Fault Tolerance for more details on fault tolerance within the autoscaling framework.
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