//(order_id, (order_date, (order_item_product_id, order_item_subtotal)))
// Get daily revenue per product id
val ordersJoinMap = ordersJoin.map(rec => ((rec._2._1, rec._2._2._1), rec._2._2._2))
ordersJoinMap.take(10).foreach(println)
ordersJoinMap.count
//((order_date, order_item_product_id), order_item_subtotal)
val dailyRevenuePerProductId = ordersJoinMap.
  reduceByKey((revenue, order_item_subtotal) => revenue + order_item_subtotal)
dailyRevenuePerProductId.take(10).foreach(println)
dailyRevenuePerProductId.count
//((order_date, order_item_product_id), daily_revenue_per_product_id)