... 22 1.3.1 Installation issues ..... 22 1.3.1.1 O1: Scala Dependency ..... 22 1.3.1.2 O2: Java gateway process exited before sending its port number ..... 22 1.3.2 Usage issues ..... 24 1.3 InaccessibleObjectException: Unable to make field private final byte[] java.lang.String.value accessible: module java.base does not “opens java.lang” to unnamed module @4e4aea35 ..... 25 1.3.4 Connector issues 20:43 flink-shaded-zookeeper-3.5.9.jar # -rw-r--r-- 1 dianfu staff 15M 10 18 20:43 flink-table-api-java-uber-1.15.2.jar # -rw-r--r-- 1 dianfu staff 35M 10 18 20:43 flink-table-planner-loader-1.15.2.jar

... 22 1.3.1 Installation issues ..... 22 1.3.1.1 O1: Scala Dependency ..... 22 1.3.1.2 O2: Java gateway process exited before sending its port number ..... 22 1.3.2 Usage issues ..... 24 1.3 InaccessibleObjectException: Unable to make field private final byte[] java.lang.String.value accessible: module java.base does not “opens java.lang” to unnamed module @4e4aea35 ..... 25 1.3.4 Connector issues 20:43 flink-shaded-zookeeper-3.5.9.jar # -rw-r--r-- 1 dianfu staff 15M 10 18 20:43 flink-table-api-java-uber-1.15.2.jar # -rw-r--r-- 1 dianfu staff 35M 10 18 20:43 flink-table-planner-loader-1.15.2.jar

• A Java 8.x installation. To develop Flink applications and use its DataStream API in Java or Scala you will need a Java JDK. A Java JRE is not sufficient! • Apache Maven 3.x. - An IDE for Java and/or

T • ListState.add(value: T) • ListState.addAll(values: java.util.List[T]). • List State.get(): Iterable[T] • ListState.update(values: java.util.List[T]) ## Flink's state primitives • MapState[K call. - A function can only access the state that belongs to the record it currently processes. ## Java example StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment(); env = rides.connect(fares) .flatMap(new MatchFunction()); ### Java example (cont.) public static class EnrichmentFunction extends RichCoFlatMapFunction

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|性能|一般(分钟小时级别)|快(秒级)|优秀 x2| |稳定性|好|一般|已在阿里内部验证| |API|差(MR)|最丰富(RDD/DataSet/DataFrame)Python/Scala/R/Java|丰富(TableAPI)Scala/Java| |SQL|HiveSQL|SparkSQL|ANSI SQL| |易用性|一般|易用|一般| |工具/生态|一般|丰富|一般| ## Flink Batch应用 - 数据湖

case class Reading(id: String, time: Long, temp: Double) Flink programs are defined in regular Scala/Java methods Set up the execution environment: local, cluster, I/O, time semantics, parallelism, ... ## nt_out Run with a class entry point and arguments: ./bin/flink run -c org.apache.flink.examples.java.wordcount.WordCount \ ./examples/batch/WordCount.jar \ --input file:///home/user/Hamlet.txt --output

based index! String name = person.f0; Integer age = person.f1; ## POJOs A POJO (plain old Java object) is any Java class that • has an empty default constructor • all fields are either • public, or

49f72cd/p39_1.jpg) A series of transformations on streams in Stream SQL, Scala, Python, Rust, Java...  dataflow graph |---|---|---| |Input|in-order|out-of-order| |Results|approximate|exact| |Language|SQL extensions, CQL|Java, Scala, Python, SQL| |Execution|centralized|distributed| |Parallelism|pipeline|pipeline, task, data|

Revisiting the basics A series of transformations on streams in Stream SQL, Scala, Python, Rust, Java...  ## Dataflow graph