cloud-fan commented on a change in pull request #28685: URL: https://github.com/apache/spark/pull/28685#discussion_r469316746
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/windowExpressions.scala ########## @@ -474,6 +479,52 @@ case class Lag(input: Expression, offset: Expression, default: Expression) override val direction = Descending } +/** + * The NthValue function returns the value of `input` at the row that is the `offset`th row of + * the window frame (counting from 1). Offsets start at 0, which is the current row. When the + * value of `input` is null at the `offset`th row or there is no such an `offset`th row, null + * is returned. + * + * @param input expression to evaluate `offset`th row of the window frame. + * @param offset rows to jump ahead in the partition. + */ +@ExpressionDescription( + usage = """ + _FUNC_(input[, offset]) - Returns the value of `input` at the row that is the`offset`th row Review comment: nit: add a space between `the` and `offset` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org