I was very impressed with the amount of material available from https://github.com/databricks/Spark-The-Definitive-Guide/ Over 450+ * megabytes.* <https://www.google.com/search?safe=strict&client=ubuntu&hs=TRK&channel=fs&sxsrf=ALeKk03x1cgbXY4fOsCpCDlXYBqobvJi4w:1585344152905&q=megabytes&spell=1&sa=X&ved=2ahUKEwizm9KYy7voAhWQO8AKHYCSCz8QkeECKAB6BAgWECc>
I have a corrected the scala code by adding *.sort(desc("sum(total_cost)"))* to the code provided on page 34 (see below). I have noticed numerous uses of exclamation marks almost over use. for example: page 23: Let's specify some more *transformatrions !* page 24: you've read your first explain *plan !* page 26: Notice that these plans compile to the exactsame underlying *plan !* page 29: The last step is our *action !* page 34: The best thing about structured streaming ....rapidly... with *virtually no code * 1. I have never read a science book with such emotion of frustration. Is Spark difficult to understand made more complicated with the proliferation of languages scala , Java , python SQL R. 2. Secondly, Is spark architecture made more complex due to competing technologies ? I have spark cluster setup with master and slave to load balancing heavy activity like so: sbin/start-master.sh sbin/start-slave.sh spark://192.168.0.38:7077 for load balancing I imagine, conceptually speaking, although I haven't tried it , I can have as many slaves(workers) on other physical machines by simply downloading spark zip file and running workers from those other physical machine(s) with sbin/start-slave.sh spark://192.168.0.38:7077. *My question is under the circumstances do I need to bother with mesos or yarn ?* Collins dictionary The exclamation mark is used after exclamations and emphatic expressions. - I can’t believe it! - Oh, no! Look at this mess! The exclamation mark loses its effect if it is overused. It is better to use a full stop after a sentence expressing mild excitement or humour. It was such a beautiful day. I felt like a perfect banana. import org.apache.spark.sql.SparkSession import org.apache.spark.sql.functions.{window,column,desc,col} object RetailData { def main(args: Array[String]): Unit = { val spark = SparkSession.builder().master("spark://192.168.0.38:7077").appName("Retail Data").getOrCreate(); // create a static frame val staticDataFrame = spark.read.format("csv") .option ("header","true") .option("inferschema","true") .load("/data/retail-data/by-day/*.csv") staticDataFrame.createOrReplaceTempView("retail_data") val staticFrame = staticDataFrame.schema staticDataFrame .selectExpr( "CustomerId","UnitPrice * Quantity as total_cost", "InvoiceDate") .groupBy(col("CustomerId"), window(col("InvoiceDate"), "1 day")) .sum("total_cost") .sort(desc("sum(total_cost)")) .show(1) } // main } // object Backbutton.co.uk ¯\_(ツ)_/¯ ♡۶Java♡۶RMI ♡۶ Make Use Method {MUM} makeuse.org <http://www.backbutton.co.uk>