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apache-kafkakafka-consumer-apiapache-kafka-streamsspring-kafka

Is GlobalKTable equivalent to KTable if num.standby.replicas = 4?

Suppose we have 4 Kafka stream instances performing a stateful operation and if num.standby.replicas = 4, isn't this configuration equal to using a GlobalKTable instead of KTable?

Solution

  • Not really.

    It's true that with a GlobalKTable all partitions are fully available on each Kafka Streams application instance. But the use case for a GlobalKTable is for holding relatively static data that users can leverage for enriching joins with a KStream.

    Additionally, you can't perform any stateful operations with a GlobalKTable, and there aren't any that return a GlobalTable. So for a quick return to processing in the face of losing an application instance, you'll still need to use standby replicas.