/**
* Copyright 2009 The Apache Software Foundation
*
* 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 org.apache.hadoop.hbase.mapreduce;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
/**
* Export an HBase table.
* Writes content to sequence files up in HDFS. Use {@link Import} to read it
* back in again.
*/
public class Export {
final static String NAME = "export";
/**
* Mapper.
*/
static class Exporter
extends TableMapper<ImmutableBytesWritable, Result> {
/**
* @param row The current table row key.
* @param value The columns.
* @param context The current context.
* @throws IOException When something is broken with the data.
* @see org.apache.hadoop.mapreduce.Mapper#map(KEYIN, VALUEIN,
* org.apache.hadoop.mapreduce.Mapper.Context)
*/
@Override
public void map(ImmutableBytesWritable row, Result value,
Context context)
throws IOException {
try {
context.write(row, value);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
/**
* Sets up the actual job.
*
* @param conf The current configuration.
* @param args The command line parameters.
* @return The newly created job.
* @throws IOException When setting up the job fails.
*/
public static Job createSubmittableJob(Configuration conf, String[] args)
throws IOException {
String tableName = args[0];
Path outputDir = new Path(args[1]);
Job job = new Job(conf, NAME + "_" + tableName);
job.setJarByClass(Exporter.class);
// TODO: Allow passing filter and subset of rows/columns.
TableMapReduceUtil.initTableMapperJob(tableName, new Scan(),
Exporter.class, null, null, job);
// No reducers. Just write straight to output files.
job.setNumReduceTasks(0);
job.setOutputFormatClass(SequenceFileOutputFormat.class);
job.setOutputKeyClass(ImmutableBytesWritable.class);
job.setOutputValueClass(Result.class);
FileOutputFormat.setOutputPath(job, outputDir);
return job;
}
/*
* @param errorMsg Error message. Can be null.
*/
private static void usage(final String errorMsg) {
if (errorMsg != null && errorMsg.length() > 0) {
System.err.println("ERROR: " + errorMsg);
}
System.err.println("Usage: Export <tablename> <outputdir>");
}
/**
* Main entry point.
*
* @param args The command line parameters.
* @throws Exception When running the job fails.
*/
public static void main(String[] args) throws Exception {
HBaseConfiguration conf = new HBaseConfiguration();
String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
if (otherArgs.length < 2) {
usage("Wrong number of arguments: " + otherArgs.length);
System.exit(-1);
}
Job job = createSubmittableJob(conf, otherArgs);
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}