scala

问题 Spark Streaming Saving data to MySQL with foreachRDD() in Scala Please, can somebody give me a functional example about saving an Spark Streaming to MySQL DB using foreachRDD() in Scala. I have below code but it's not working. I just need a simple example, not sintaxis or theory. Thank you! package examples import org.apache.spark.{SparkConf, SparkContext} import org.apache.spark._ import org.apache.spark.storage.StorageLevel import org.apache.spark.streaming.{Seconds, StreamingContext}

问题 I am confused about why Scala is complaining about this code. I have two classes which depend on each other. When I try to create a new instance of A without a type declaration, the code won't compile. class A( b:B ) { } class B( a:A ){ } val y = new A ( new B( y ) ); // gives recursive value y needs type val z:A = new A ( new B( y ) ); // ok Why does the compiler does not know the type of y when I declared as new A ? 回答1: To infer the type of y , the compiler must first determine the type of

问题 How do I convert a Set("a","b","c") to a Map("a"->1,"b"->2,"c"->3)? I think it should work with toMap. 回答1: zipWithIndex is probably what you are looking for. It will take your collection of letters and make a new collection of Tuples, matching value with position in the collection. You have an extra requirement though - it looks like your positions start with 1, rather than 0, so you'll need to transform those Tuples: Set("a","b","c") .zipWithIndex //(a,0), (b,1), (c,2) .map{case(v,i) => (v,

问题 I have observed weird behavior in spark date formatting. Actually I need to convert the date yy to yyyy . After date conversion it should be 20yy in date I have tried as below, it failing after 2040 year. import org.apache.spark.sql.functions._ val df= Seq(("06/03/35"),("07/24/40"), ("11/15/43"), ("12/15/12"), ("11/15/20"), ("12/12/22")).toDF("Date") df.withColumn("newdate", from_unixtime(unix_timestamp($"Date", "mm/dd/yy"), "mm/dd/yyyy")).show +--------+----------+ | Date| newdate| +--------

问题 I am working on a complex logic where I need to redistribute a quantity from one dataset to another dataset. In the example we have Owner and Invoice - We need to subtract the quantity from the Invoice to the exact Owner match (at a given postal code for a given car). The subtracted quantity needs to be redistributed back to the other postal code where the same car appears. The complexity happens where we should avoid distributing to postal code where the same car is present in the Invoice

问题 Is foreach by-definition guaranteed to iterate the subject collection (if it defines order) sequentially from the very first to the very last (unless accidentally interrupted) element? Aren't there any compiler optimization switches which can brake it (shuffle the sequence) or plans to make the ordinary foreach parallel in future versions? 回答1: Foreach is guaranteed to be sequential for sequential collections (that is, the normal hierarchy, or for anything transformed by .seq ). The parallel

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed yesterday . Improve this question when i run gatlingRun task it is complain about object intuit is not a member of package com not found all my scala class under src/gatling/simulations folder dependencies { compile group: 'com.intuit.karate', name: 'karate-gatling', version: karateVersion

问题 The following code runs into future timeouts (in Scala 2.x and Dotty, -Xcheckinit or -Ycheck-init does not help here) because of cyclic object initialization. In complex projects these cycles usually are hidden very well. Is there any possiblity of getting help from the compiler or at least at runtime? How do you prevent this from happening in a multithreaded environment? import scala.concurrent.Future import scala.concurrent._ import scala.concurrent.duration._ import scala.concurrent

问题 I am saving a puts RDD to Hbase using saveAsNewAPIHadoopDataset. Below is my job creation and submition. val outputTableName = "test3" val conf2 = HBaseConfiguration.create() conf2.set("hbase.zookeeper.quorum", "xx.xx.xx.xx") conf2.set("hbase.mapred.outputtable", outputTableName) conf2.set("mapreduce.outputformat.class", "org.apache.hadoop.hbase.mapreduce.TableOutputFormat") val job = createJob(outputTableName, conf2) val outputTable = sc.broadcast(outputTableName) val hbasePuts = simpleRdd

问题 I am saving a puts RDD to Hbase using saveAsNewAPIHadoopDataset. Below is my job creation and submition. val outputTableName = "test3" val conf2 = HBaseConfiguration.create() conf2.set("hbase.zookeeper.quorum", "xx.xx.xx.xx") conf2.set("hbase.mapred.outputtable", outputTableName) conf2.set("mapreduce.outputformat.class", "org.apache.hadoop.hbase.mapreduce.TableOutputFormat") val job = createJob(outputTableName, conf2) val outputTable = sc.broadcast(outputTableName) val hbasePuts = simpleRdd