Hi, all. I created the JIRA https://issues.apache.org/jira/browse/FLINK-4856 to
propose adding MapStates into Flink.
MapStates are very useful in our daily jobs. For example, when implementing
DistinctCount, we store the values into a MapState and the result of each
group(key) is exactly the number of entries in the MapState.
In my opinion, the methods provided by the MapState may include:
* void put(K key, V value)
* V get(K key)
* Iterable<K> keys()
* Iterable<V> values()
* Iterator<Tuple2<K, V>> iterator()
Do you have any comments? Any is appreciated.