Q31. How provenance repository does provides search capability?
Ans: Provenance repository uses the embedded Lucene search engine.

Q32. Can we re-process the FlowFile, which has already been processed and how?

Ans: Yes, we can re-process the FlowFile which had already been processed from Data Provenance repository. Replay button that allows the user to re-insert the FlowFile into the flow and re-process it from exactly the point at which the event happened. This provides a very powerful mechanism, as we are able to modify our flow in real time, re-process a FlowFile, and then view the results. If they are not as expected, we can modify the flow again, and re-process the FlowFile again. We are able to perform this iterative development of the flow until it is processing the data exactly as intended.

Q33. What is the use of Flow Controller?

Ans: The flow controller is the brains of the operation. It provides threads for extensions to run on, and manages the schedule of when extensions receive resources to execute. The Flow Controller acts as the engine dictating when a particular processor is given a thread to execute.

Q34. What is process group in NiFi?

Ans: Process group can help you to create sub data flow. Which you can add in your main dataflow. You can send and receive data from process group using output port and input port respectively.  You can say it is a composition of the NiFi components to create a sub dataflow.

Q35. What is the difference between FlowFile and Content repository in NiFi?

Ans: The FlowFile Repository is where NiFi keeps track of the state of what it knows about a given FlowFile that is presently active in the flow.

The Content Repository is where the actual content bytes of a given FlowFile live.