Hi Joe, 

Thanks for the reply. The actual flow is sending data from the ConsumeAMQP 
processor to two different PublishKafka processors, one with Idempotence and 
other with default config. Each of it is sending same data to two different 
topics and comparing both topics is how I am checking that there are 
duplicates. It seems to be random, some times they appear in the "normal" 
processor's topic and others in the "idempotence", I did not find any pattern. 

I will upgrade to NiFi 1.18.0 and try again. 

In any case, messages have json format (one json per flowfile) but since I am 
sending and storing them in kafka in plain text I am using no-record-oriented 
Kafka publisher. Is PublishKafkaRecord more reliable? Would it be better to use 
it? 

Thanks, 

Aian 


De: "Joe Witt" <[email protected]> 
Para: "users" <[email protected]> 
Enviados: Martes, 15 de Noviembre 2022 17:31:54 
Asunto: Re: Exacly once from NiFi to Kafka 

Aian, 
How can you tell there are duplicates in Kafka and are you certain that no 
duplicates exist in the source topic? 

Given NiFi's data provenance capabilities you should be able to pin point a 
given duplicate and figure out whether it happened at the source, in nifi, or 
otherwise. 

Note much has changed/improved since the 1.12.x line of NiFi so we have more 
Kafka components and record oriented mechanisms. But still pretty sure even in 
your version we should not be duplicating data unless the flow is configured 
such that it would happen. 

Thanks 

On Tue, Nov 15, 2022 at 9:25 AM Aian Cantabrana < [ mailto:[email protected] 
| [email protected] ] > wrote: 



Hi, 

I am having some difficulties trying to get exactly-once semantic while 
ensuring data order from NiFi to Kafka. I have read Kafka documentation and it 
should be quite straight forward using idempotent producer from NiFi and having 
a Kafka topic with a single partition, but I am still getting some duplicated 
messages in Kafka. 

NiFi version: 1.12.1 
Kafka version: 2.7.0 

NiFi flow: 
(Both shown queues with FIFO prioritizer) 

PublishKafka_2_6 configuration: 

As I said, target Kafka topic has just one partition to ensure data order. 

Incoming flowfiles are small 60 bytes messages. 

I have been a while working with it so any suggestion is really welcome. 

Thanks in advance, 

Aian 




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