Tasks are run on middle managers and always operate on a single data source.
Tasks are submitted using POST requests to the Overlord. Please see Overlord Task API for API details.
There are several different types of tasks.
See batch ingestion.
Druid provides a native index task which doesn't need any dependencies on other systems. See native index tasks for more details.
Kafka Indexing tasks are automatically created by a Kafka Supervisor and are responsible for pulling data from Kafka streams. These tasks are not meant to be created/submitted directly by users. See Kafka Indexing Service for more details.
Tranquility Server automatically creates "realtime" tasks that receive events over HTTP using an EventReceiverFirehose. These tasks are not meant to be created/submitted directly by users. See Tranquility Stream Push for more info.
Compaction tasks merge all segments of the given interval. Please see Compaction for details.
Kill tasks delete all information about a segment and removes it from deep storage.
Please see Deleting Data for details.
Please see Miscellaneous Tasks.
Please see Task Locking and Priority.