scala

Is there better way to display entire Spark SQL DataFrame?

由 泄露秘密 提交于 2020-12-27 07:57:05
问题 I would like to display the entire Apache Spark SQL DataFrame with the Scala API. I can use the show() method: myDataFrame.show(Int.MaxValue) Is there a better way to display an entire DataFrame than using Int.MaxValue ? 回答1: It is generally not advisable to display an entire DataFrame to stdout, because that means you need to pull the entire DataFrame (all of its values) to the driver (unless DataFrame is already local, which you can check with df.isLocal ). Unless you know ahead of time

flink学习笔记-flink实战

由 百般思念 提交于 2020-12-27 03:49:43
说明：本文为《 Flink 大数据项目实战》学习笔记，想通过视频系统学习 Flink 这个最火爆的大数据计算框架的同学，推荐学习课程： Flink 大数据项目实战： http://t.cn/EJtKhaz 2.4 字段表达式实例 -Java 以下定义两个 Java 类： public static class WC { public ComplexNestedClass complex; private int count; public int getCount() { return count; } public void setCount(int c) { this.count = c; } } public static class ComplexNestedClass { public Integer someNumber; public float someFloat; public Tuple3<Long, Long, String> word; public IntWritable hadoopCitizen; } 我们一起看看如下 key 字段如何理解： 1."count": wc 类的 count 字段 2."complex": 递归的选取 ComplexNestedClass 的所有字段 3."complex.word.f2":

how to resolve conflict of ActorSystem in akka http test and akka test kit

由 ▼魔方 西西 提交于 2020-12-26 11:11:17
问题 i have a test class in which i need to use both akka testkit and akka http test kit so i am doing it like this class MyTest extends TestKit(ActorSystem("testsys")) with ScalaFutures with ImplicitSender with AnyWordSpecLike with Matchers with BeforeAndAfterAll with ScalatestRouteTest { //tests here } but i am getting a compile time error implicit val system: akka.actor.ActorSystem (defined in class TestKit) and [error] implicit val system: akka.actor.ActorSystem (defined in trait RouteTest)

how to resolve conflict of ActorSystem in akka http test and akka test kit

由 雨燕双飞 提交于 2020-12-26 11:08:14
问题 i have a test class in which i need to use both akka testkit and akka http test kit so i am doing it like this class MyTest extends TestKit(ActorSystem("testsys")) with ScalaFutures with ImplicitSender with AnyWordSpecLike with Matchers with BeforeAndAfterAll with ScalatestRouteTest { //tests here } but i am getting a compile time error implicit val system: akka.actor.ActorSystem (defined in class TestKit) and [error] implicit val system: akka.actor.ActorSystem (defined in trait RouteTest)

Dynamic compilation of multiple Scala classes at runtime

由 依然范特西╮ 提交于 2020-12-26 01:58:54
问题 I know I can compile individual "snippets" in Scala using the Toolbox like this: import scala.reflect.runtime.universe import scala.tools.reflect.ToolBox object Compiler { val tb = universe.runtimeMirror(getClass.getClassLoader).mkToolBox() def main(args: Array[String]): Unit = { tb.eval(tb.parse("""println("hello!")""")) } } Is there any way I can compile more than just "snippets", i.e., classes that refer to each other? Like this: import scala.reflect.runtime.universe import scala.tools

Dynamic compilation of multiple Scala classes at runtime

由 為{幸葍}努か 提交于 2020-12-26 01:57:27
问题 I know I can compile individual "snippets" in Scala using the Toolbox like this: import scala.reflect.runtime.universe import scala.tools.reflect.ToolBox object Compiler { val tb = universe.runtimeMirror(getClass.getClassLoader).mkToolBox() def main(args: Array[String]): Unit = { tb.eval(tb.parse("""println("hello!")""")) } } Is there any way I can compile more than just "snippets", i.e., classes that refer to each other? Like this: import scala.reflect.runtime.universe import scala.tools

Dynamic compilation of multiple Scala classes at runtime

由 醉酒当歌 提交于 2020-12-26 01:57:06
问题 I know I can compile individual "snippets" in Scala using the Toolbox like this: import scala.reflect.runtime.universe import scala.tools.reflect.ToolBox object Compiler { val tb = universe.runtimeMirror(getClass.getClassLoader).mkToolBox() def main(args: Array[String]): Unit = { tb.eval(tb.parse("""println("hello!")""")) } } Is there any way I can compile more than just "snippets", i.e., classes that refer to each other? Like this: import scala.reflect.runtime.universe import scala.tools

【spark系列5】spark 3.0.1集成delta 0.7.0原理解析--delta如何进行DDL DML操作以及Catalog plugin API

由 生来就可爱ヽ(ⅴ＜●) 提交于 2020-12-25 16:37:17
前提 本文基于 spark 3.0.1 delta 0.7.0 我们都知道delta.io是一个给数据湖提供可靠性的开源存储层的软件，关于他的用处，可以参考 Delta Lake，让你从复杂的Lambda架构中解放出来 ,上篇文章我们分析了 delta是如何自定义自己的sql ,这篇文章我们分析一下delta数据是如何基于Catalog plugin API进行DDL DML sql操作的(spark 3.x以前是不支持的) 分析 delta在0.7.0以前是不能够进行save表操作的，只能存储到文件中，也就是说他的元数据是和spark的其他元数据是分开的，delta是独立存在的，也是不能和其他表进行关联操作的，只有到了delta 0.7.0版本以后，才真正意义上和spark进行了集成，这也得益于spark 3.x的Catalog plugin API 特性。 还是先从delta的 configurate sparksession 入手,如下: import org.apache.spark.sql.SparkSession val spark = SparkSession .builder() .appName("...") .master("...") .config("spark.sql.extensions", "io.delta.sql

Listing files from resource directory in sbt 1.2.8

由 六月ゝ 毕业季﹏ 提交于 2020-12-25 08:46:31
问题 I have a Scala application which processes binary files from some directory in resources . I would like to get this directory as java.io.File and list all the contents. In the newest sbt I am unable to do it the straight way. I have created minimal repo with my issue: https://github.com/mat646/sbt-resource-bug The issue does not occur with sbt 0.13.18 and lower. So after some research I've found out that since sbt 1.0 the design has changed and such issue has been already addressed here:

Listing files from resource directory in sbt 1.2.8

由 a 夏天 提交于 2020-12-25 08:45:00
问题 I have a Scala application which processes binary files from some directory in resources . I would like to get this directory as java.io.File and list all the contents. In the newest sbt I am unable to do it the straight way. I have created minimal repo with my issue: https://github.com/mat646/sbt-resource-bug The issue does not occur with sbt 0.13.18 and lower. So after some research I've found out that since sbt 1.0 the design has changed and such issue has been already addressed here:
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