tdas commented on a change in pull request #33093:
URL: https://github.com/apache/spark/pull/33093#discussion_r662282624
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/KeyValueGroupedDataset.scala
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@@ -280,6 +280,51 @@ class KeyValueGroupedDataset[K, V] private[sql](
child = logicalPlan))
}
+ /**
+ * (Scala-specific)
+ * Applies the given function to each group of data, while maintaining a
user-defined per-group
+ * state. The result Dataset will represent the objects returned by the
function.
+ * For a static batch Dataset, the function will be invoked once per group.
For a streaming
+ * Dataset, the function will be invoked for each group repeatedly in every
trigger, and
+ * updates to each group's state will be saved across invocations.
+ * See [[org.apache.spark.sql.streaming.GroupState]] for more details.
+ *
+ * @tparam S The type of the user-defined state. Must be encodable to Spark
SQL types.
+ * @tparam U The type of the output objects. Must be encodable to Spark SQL
types.
+ * @param func Function to be called on every group.
+ * @param timeoutConf Timeout Conf, see GroupStateTimeout for more details
+ * @param initialState The user provided state that will be initialized when
the first batch
+ * of data is processed in the streaming query. The user
defined function
+ * will be called on the state data even if there are no
other values in
+ * the group. To convert a Dataset ds of type
Dataset[(K, S)] to a
Review comment:
```
To covert a Dataset `ds` of type of type `Dataset[(K, S)]` .... to a
`KeyValueGroupedDataset[K, S]`, use ...
```
change in other places as well
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