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I have two Kafka streams applications running on two different nodes. Brokers are 5. Replication factor of topics and changelog topics is 2. Now I want to increase or decrease replication factor for internal topics. Would this affect my running Kafka Streams? Do I have to restart applications for the change to take place or do I have to change application ids for streams? If yes, is there any strong reason for that?

Same is question for changing standy by replicas of stores (e.g NUM_STANDBY_REPLICAS_CONFIG)?

Thank you.

Sagar
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Changing replication factor would not affect the topology, because (hopefully) the leader brokers of each partition are not changing while the replication process occurs

Should you chose to lower the replication factor, thus removing leadership while the application is running, then you would see errors like "broker is not assigned partition"

OneCricketeer
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  • is that mean lowering replication factor of internal topic will cause issues so I have to change application ids for streams, while increasing replication factor wouldn't cause any issue? Am I getting this right? – Sagar Mar 29 '20 at 12:46
  • In general, I have never lowered replication factor. That just seems like a bad idea. But yes, you would have to reset the topology and clean internal topics either via the CLI command or by chaning the application id – OneCricketeer Mar 29 '20 at 23:55
  • Increasing replication factor of internal topics would not affect topolgy right? It will only cause issue while lowering the number. I think I got my answer. Thank you. – Sagar Mar 30 '20 at 00:11