Status
Current state: Under Discussion
Discussion thread: tba
JIRA: KAFKA-6037
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
Motivation
- The main motivation of this KIP is stated in the related jira: "Today the downstream sub-topology's parallelism (aka the number of tasks) are purely dependent on the upstream sub-topology's parallelism, which ultimately depends on the source topic's num. partitions. However this does not work perfectly with dynamic scaling scenarios".
- Depending on use-case, we might not need to use repartitioning topic, as keys might not change.
Proposed Changes
public class Produced<K, V> { protected String topicName; protected Boolean topicCreated = false; protected Boolean repartitionNeeded = true; protected Boolean useAsInternalTopicOnly = true; protected Integer partitions; protected Produced(String topicName, Boolean alreadyCreated) { this.topicName = topicName; this.alreadyCreated = alreadyCreated; } protected Produced(String topicName, Integer partitions) { this.topicName = topicName; this.partitions = partitions; } public static <K, V> Produced<K, V> withTopic(String topicName, Boolean alreadyCreated) { return new Produced<>(topicName, alreadyCreated); } public static <K, V> Produced<K, V> withTopic(String topicName, Integer partitions) { return new Produced<>(topicName, partitions); } public Produced<K, V> repartitionNeeded(Boolean repartitionNeeded) { this.repartitionNeeded = repartitionNeeded; return this; } public Produced<K, V> useAsInternalTopicOnly(Boolean useAsInternalTopicOnly) { this.useAsInternalTopicOnly = useAsInternalTopicOnly; return this; } }
Public interfaces
We try to avoid many overloads by not implementing all the overloaded combinations of related methods.
KStream
KStream<K, V> through(final Produced topicInfo); void to(final Produced topicInfo);
Rejected Alternatives
If there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.