There are documents such as the ones below stating that Kafka topic-level configuration changes can be taken place while Kafka cluster is still running.
The questions I have are:
When will the configuration change take effect? Is restart of Kafka cluster required? https://community.cloudera.com/t5/Support-Questions/Kafka-alter-topic-requires-broker-restart-to-take-effect/td-p/44396
Are there differences for config change effect to kick in different topic-level config? http://kafka.apache.org/documentation/#topicconfigs