Github user tejasapatil commented on a diff in the pull request: https://github.com/apache/spark/pull/16909#discussion_r105093397 --- Diff: sql/core/src/main/scala/org/apache/spark/sql/execution/window/WindowFunctionFrame.scala --- @@ -341,25 +364,27 @@ private[window] final class UnboundedFollowingWindowFunctionFrame( override def write(index: Int, current: InternalRow): Unit = { var bufferUpdated = index == 0 - // Duplicate the input to have a new iterator - val tmp = input.copy() - - // Drop all rows from the buffer for which the input row value is smaller than + // Ignore all the rows from the buffer for which the input row value is smaller than // the output row lower bound. - tmp.skip(inputIndex) - var nextRow = tmp.next() + val iterator = input.generateIterator(startIndex = inputIndex) + + def getNextOrNull(iterator: Iterator[UnsafeRow]): UnsafeRow = { --- End diff -- @hvanhovell @davies : In case of windowing, there are no nulls expected so `null` is being used as an indicator for no more data left to be read. Earlier this was being done in `RowBuffer.next` [0] which this PR gets rid of (notice that its not throwing any exception once the end is reached). Adding this as a method in iterator class might be bad given this assumption specific to windowing usage (ie. no nulls). I have created a static method within `WindowFunctionFrame` so that there would be sharing amongst all the windowing frame implementations. [0] : https://github.com/apache/spark/blob/417140e441505f20eb5bd4943ce216c3ec6adc10/sql/core/src/main/scala/org/apache/spark/sql/execution/window/RowBuffer.scala#L37
--- If your project is set up for it, you can reply to this email and have your reply appear on GitHub as well. If your project does not have this feature enabled and wishes so, or if the feature is enabled but not working, please contact infrastructure at infrastruct...@apache.org or file a JIRA ticket with INFRA. --- --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org