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KeyedStream<T, Tuple> localKeyBy(int… fields);
KeyedStream<T, Tuple> localKeyBy(Keys<T> keys);
<K> KeyedStream<T, K> localKeyBy(KeySelector<T, K> keySelector);
<K> KeyedStream<T, K> localKeyBy(KeySelector<T, K> keySelector, TypeInformation<K> keyType);

Design

Users can perform local aggregation with local keyed streams. Local keyed streams resemble keyed streams in many respects. They both partition elements according to keys and allow access to states affiliated with keys. But the partitioning in local keyed streams does not require shuffling and is performed locally.

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