it.crs4.pydoop.WriteParquet.java Source code

Introduction

Here is the source code for it.crs4.pydoop.WriteParquet.java

Source

/* BEGIN_COPYRIGHT
 *
 * Copyright 2009-2015 CRS4.
 *
 * Licensed 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.
 *
 * END_COPYRIGHT
 *
 * A MapReduce application that reads ';'-separated text and writes
 * parquet-avro data (i.e., Parquet files that use the Avro object model).
 *
 * Based on Cloudera Parquet examples.
 */

package it.crs4.pydoop;

import java.io.IOException;
import java.io.InputStream;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.Mapper.Context;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;

import parquet.Log;
import parquet.avro.AvroParquetOutputFormat;

import org.apache.avro.generic.GenericData.Record;
import org.apache.avro.Schema;

public class WriteParquet extends Configured implements Tool {

    private static final Log LOG = Log.getLog(WriteParquet.class);

    // FIXME: not needed, we're calling setSchema below
    private static final String SCHEMA_PATH_KEY = "paexample.schema.path";

    private static Schema getSchema(Configuration conf) throws IOException {
        Path schemaPath = new Path(conf.get(SCHEMA_PATH_KEY));
        FileSystem fs = FileSystem.get(conf);
        InputStream in = fs.open(schemaPath);
        Schema schema = new Schema.Parser().parse(in);
        in.close();
        return schema;
    }

    public static class WriteUserMap extends Mapper<LongWritable, Text, NullWritable, Record> {

        private Schema schema;

        @Override
        public void setup(Context context) throws IOException, InterruptedException {
            schema = getSchema(context.getConfiguration());
        }

        @Override
        public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
            NullWritable outKey = NullWritable.get();
            Record user = new Record(schema);
            String[] elements = value.toString().split(";");
            user.put("name", elements[0]);
            user.put("office", elements[1]);
            user.put("favorite_color", elements[2]);
            context.write(null, user);
        }
    }

    public int run(String[] args) throws Exception {

        if (args.length < 3) {
            System.err.println("Usage: WriteParquet <input path> <output path> <schema path>");
            return -1;
        }
        Path inputPath = new Path(args[0]);
        Path outputPath = new Path(args[1]);
        String schemaPathName = args[2];

        Configuration conf = getConf();
        conf.set(SCHEMA_PATH_KEY, schemaPathName);
        Schema schema = getSchema(conf);

        Job job = new Job(conf);
        job.setJarByClass(getClass());
        job.setJobName(getClass().getName());

        AvroParquetOutputFormat.setSchema(job, schema);

        job.setMapperClass(WriteUserMap.class);
        job.setNumReduceTasks(0);
        job.setInputFormatClass(TextInputFormat.class);
        job.setOutputFormatClass(AvroParquetOutputFormat.class);

        FileInputFormat.setInputPaths(job, inputPath);
        FileOutputFormat.setOutputPath(job, outputPath);

        job.waitForCompletion(true);

        return 0;
    }

    public static void main(String[] args) throws Exception {
        try {
            int res = ToolRunner.run(new Configuration(), new WriteParquet(), args);
            System.exit(res);
        } catch (Exception e) {
            e.printStackTrace();
            System.exit(255);
        }
    }
}