Xingcan Cui created FLINK-6936:
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Summary: Add multiple targets support for custom partitioner
Key: FLINK-6936
URL: https://issues.apache.org/jira/browse/FLINK-6936
Project: Flink
Issue Type: Improvement
Components: DataStream API
Reporter: Xingcan Cui
Assignee: Xingcan Cui
Priority: Minor
The current user-facing Partitioner only allows returning one target.
{code:java}
@Public
public interface Partitioner<K> extends java.io.Serializable, Function {
/**
* Computes the partition for the given key.
*
* @param key The key.
* @param numPartitions The number of partitions to partition into.
* @return The partition index.
*/
int partition(K key, int numPartitions);
}
{code}
Actually, this function should return multiple partitions and this may be a
historical legacy.
There could be at least three approaches to solve this.
# Make the `protected DataStream<T> setConnectionType(StreamPartitioner<T>
partitioner)` method in DataStream public and that allows users to directly
define StreamPartitioner.
# Change the `partition` method in the Partitioner interface to return an int
array instead of a single int value.
# Add a new `multicast` method to DataStream and provide a MultiPartitioner
interface which returns an int array.
Considering the consistency of API, the 3rd approach seems to be an acceptable
choice. [~aljoscha], what do you think?
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