AVG window function

AVG-window-function.scala

import org.apache.spark.sql.expressions.Window
import org.apache.spark.sql.functions._

val winsales = spark.table("winsales")

val windowSpec = Window.orderBy(col("dateid"), col("salesid")).rowsBetween(Window.unboundedPreceding, Window.currentRow)

val result = winsales
  .select(col("salesid"), col("dateid"), col("sellerid"), col("qty"),
    avg(col("qty")).over(windowSpec).as("avg"))
  .orderBy(col("dateid"), col("salesid"))

result.show()

//https://docs.aws.amazon.com/redshift/latest/dg/r_WF_AVG.html