dbx.compute.spark.jobs.sql.hive.JavaSparkHiveExample.java Source code

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Here is the source code for dbx.compute.spark.jobs.sql.hive.JavaSparkHiveExample.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file 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
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package dbx.compute.spark.jobs.sql.hive;

// $example on:spark_hive$
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import org.apache.spark.api.java.function.MapFunction;
import org.apache.spark.sql.Dataset;
import org.apache.spark.sql.Encoders;
import org.apache.spark.sql.Row;
import org.apache.spark.sql.SparkSession;
// $example off:spark_hive$

public class JavaSparkHiveExample {

    // $example on:spark_hive$
    public static class Record implements Serializable {
        private int key;
        private String value;

        public int getKey() {
            return key;
        }

        public void setKey(int key) {
            this.key = key;
        }

        public String getValue() {
            return value;
        }

        public void setValue(String value) {
            this.value = value;
        }
    }
    // $example off:spark_hive$

    public static void main(String[] args) {
        // $example on:spark_hive$
        // warehouseLocation points to the default location for managed databases and tables
        String warehouseLocation = "file:" + System.getProperty("user.dir") + "spark-warehouse";
        SparkSession spark = SparkSession.builder().appName("Java Spark Hive Example")
                .config("spark.sql.warehouse.dir", warehouseLocation).enableHiveSupport().getOrCreate();

        spark.sql("CREATE TABLE IF NOT EXISTS src (key INT, value STRING)");
        spark.sql("LOAD DATA LOCAL INPATH 'examples/src/main/resources/kv1.txt' INTO TABLE src");

        // Queries are expressed in HiveQL
        spark.sql("SELECT * FROM src").show();
        // +---+-------+
        // |key|  value|
        // +---+-------+
        // |238|val_238|
        // | 86| val_86|
        // |311|val_311|
        // ...

        // Aggregation queries are also supported.
        spark.sql("SELECT COUNT(*) FROM src").show();
        // +--------+
        // |count(1)|
        // +--------+
        // |    500 |
        // +--------+

        // The results of SQL queries are themselves DataFrames and support all normal functions.
        Dataset<Row> sqlDF = spark.sql("SELECT key, value FROM src WHERE key < 10 ORDER BY key");

        // The items in DaraFrames are of type Row, which lets you to access each column by ordinal.
        Dataset<String> stringsDS = sqlDF.map(new MapFunction<Row, String>() {
            public String call(Row row) throws Exception {
                return "Key: " + row.get(0) + ", Value: " + row.get(1);
            }
        }, Encoders.STRING());
        stringsDS.show();
        // +--------------------+
        // |               value|
        // +--------------------+
        // |Key: 0, Value: val_0|
        // |Key: 0, Value: val_0|
        // |Key: 0, Value: val_0|
        // ...

        // You can also use DataFrames to create temporary views within a HiveContext.
        List<Record> records = new ArrayList<Record>();
        for (int key = 1; key < 100; key++) {
            Record record = new Record();
            record.setKey(key);
            record.setValue("val_" + key);
            records.add(record);
        }
        Dataset<Row> recordsDF = spark.createDataFrame(records, Record.class);
        recordsDF.createOrReplaceTempView("records");

        // Queries can then join DataFrames data with data stored in Hive.
        spark.sql("SELECT * FROM records r JOIN src s ON r.key = s.key").show();
        // +---+------+---+------+
        // |key| value|key| value|
        // +---+------+---+------+
        // |  2| val_2|  2| val_2|
        // |  2| val_2|  2| val_2|
        // |  4| val_4|  4| val_4|
        // ...
        // $example off:spark_hive$

        spark.stop();
    }
}