flink-examples/flink-examples-table/src/main/scala/org/apache/flink/table/examples/scala/WordCountTable.scala

/*
 * Licensed to the Apache Software Foundation (ASF) under one
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 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.flink.table.examples.scala

import org.apache.flink.api.scala._
import org.apache.flink.streaming.api.scala.StreamExecutionEnvironment
import org.apache.flink.table.api.TableEnvironment
import org.apache.flink.table.api.scala._

/**
  * Simple example for demonstrating the use of the Table API for a Word Count in Scala.
  *
  * This example shows how to:
  *  - Convert DataSets to Tables
  *  - Apply group, aggregate, select, and filter operations
  *
  */
object WordCountTable {

  // *************************************************************************
  //     PROGRAM
  // *************************************************************************

  def main(args: Array[String]): Unit = {

    // set up execution environment
    val execEnv = StreamExecutionEnvironment.getExecutionEnvironment
    val tEnv = TableEnvironment.getBatchTableEnvironment(execEnv)

    val input = execEnv.fromElements(WC("hello", 1), WC("hello", 1), WC("ciao", 1))
    tEnv.fromBoundedStream(input, 'word, 'frequency)
      .groupBy('word)
      .select('word, 'frequency.sum as 'frequency)
      .filter('frequency === 2)
      .print()
  }

  // *************************************************************************
  //     USER DATA TYPES
  // *************************************************************************

  case class WC(word: String, frequency: Long)

}