@FediMannoubi Below is a basic approach to solve.  Assuming both postgres tables are populated with rows per your example, your nifi flow would need to get the CSV (various ways to do that), once the contents of the csv are in a flowfile (i use GenerateFlowFile processor), you can use a RecordReader based processor to read the csv.  This will allow you to write SQL against the flowfile with QueryRecord to get a single value.  For example:  SELECT city_name FROM FLOWFILE  Next, in your flow you will need to get the city_name value into an attribute, i use EvaluateJsonPath.  After that a ExecuteSQL processor and associated DBCP Connection pool to postgres.  Then in ExecuteSQL your query is  SELECT city_id FROM CITY WHERE city_name=${city_name} At the end of this flow you will have the city_name from csv, and city_id from postgres.  You can now combine or use the further downstream to suit your needs.   INSERT is done similarly, once you have the data in flowfiles, or attributes, using the same ExecuteSQL you write an insert instead. My test flow looks like this, but forgive the end, as I did not actually have a postgres database setup.     You can find this sample flow [here].   I hope this gets you pointed in the right direction for reading csv and querying data from database. ... View more

@jonay__reyes   I think by default you will see the result you are expecting,  however, the expected limit of 5 concurrent connections may be a challenge.     Let's address your questions first:     Does this translate to simply using 1 InvokeHTTP processor configured to 5 "Concurrent Tasks" and that's it?  -  1 proc w/ 5 concurrent tasks, will provide what is in effect 5 instance copies and they can run more than 5 requests each if there are ample flowfiles queued up.  So, NO.  For your use case, i would recommend that you set it to 1, and control the # of flowfiles upstream. Will the processor wait for the remote endpoint's request before sending the next one?  YES if concurrent task set to 1.  NO, if set higher (2+) they will execute in parallel How does the "Run Schedule" works together with the previous settings? (if I had, e.g.: 1 sec). Run Schedule sets how long a process will operate before a new instance is necessary.  If the request/response times are low, this setting will allow you to push more data through each instance without creating separate processes for each.  If the request/response time is high, you can use this to help with long execution.  Experiment carefully here. I've been proposed with splitting the incoming queue and put 5 InvokeHTTP processors in parallel, each one attending 1/5 of the incoming flowfiles (I'd do the pre-partitioning before with some RouteOnAttribute trick), but I think it's exactly the same outcome as the 1. above. Is it?   Correct, there is no reason to do this,  avoid duplicating processors     For concurrent tasks and run schedule adjustments, you should always experiment in small increments, changing one setting at a time, evaluating, and repeating until you find the right balance.   I suspect that you will not need 5 long executing request/responses in parallel, and that even with default settings,  your queued flowfiles will execute fast enough to appear "simultaneous". ... View more

@krishna123 this is how nifi is supposed to work.   If there is no input, even though the processor is Play/Green, it is not doing anything.     It is only "running" if there is input. ... View more

@krishna123 NiFi data flows are expected to be operated in an always on capacity.  If no input is arriving, the processor is not doing anything, there is no reason to stop it.   Can you explain in more detail why you want it actually stopped?   ... View more