BroadcastMode is used to create:
Transforming InternalRows into HashedRelation (with Optional Size Hint)¶
transform( rows: Iterator[InternalRow], sizeHint: Option[Long]): Any
BroadcastExchangeExecphysical operator is requested for relationFuture
transform( rows: Array[InternalRow]): Any
transform(rows) does not seem to be used.