org.apache.hadoop.hbase.mapreduce.IndexBuilder Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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*
* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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package org.apache.hadoop.hbase.mapreduce;
import java.io.IOException;
import java.util.TreeMap;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.Put;
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.hbase.util.Bytes;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.apache.yetus.audience.InterfaceAudience;
/**
* Example map/reduce job to construct index tables that can be used to quickly find a row based on
* the value of a column. It demonstrates:
*
* - Using TableInputFormat and TableMapReduceUtil to use an HTable as input to a map/reduce
* job.
* - Passing values from main method to children via the configuration.
* - Using MultiTableOutputFormat to output to multiple tables from a map/reduce job.
* - A real use case of building a secondary index over a table.
*
* Usage
*
* Modify ${HADOOP_HOME}/conf/hadoop-env.sh to include the hbase jar, the zookeeper jar (can be
* found in lib/ directory under HBase root, the examples output directory, and the hbase conf
* directory in HADOOP_CLASSPATH, and then run
* bin/hadoop org.apache.hadoop.hbase.mapreduce.IndexBuilder
* TABLE_NAME COLUMN_FAMILY ATTR [ATTR ...]
*
*
* To run with the sample data provided in index-builder-setup.rb, use the arguments
* people attributes name email phone.
*
*
* This code was written against HBase 0.21 trunk.
*
*/
@InterfaceAudience.Private
public class IndexBuilder extends Configured implements Tool {
/** the column family containing the indexed row key */
public static final byte[] INDEX_COLUMN = Bytes.toBytes("INDEX");
/** the qualifier containing the indexed row key */
public static final byte[] INDEX_QUALIFIER = Bytes.toBytes("ROW");
/**
* Internal Mapper to be run by Hadoop.
*/
public static class Map
extends Mapper {
private byte[] family;
private TreeMap indexes;
@Override
protected void map(ImmutableBytesWritable rowKey, Result result, Context context)
throws IOException, InterruptedException {
for (java.util.Map.Entry index : indexes.entrySet()) {
byte[] qualifier = index.getKey();
ImmutableBytesWritable tableName = index.getValue();
byte[] value = result.getValue(family, qualifier);
if (value != null) {
// original: row 123 attribute:phone 555-1212
// index: row 555-1212 INDEX:ROW 123
Put put = new Put(value);
put.addColumn(INDEX_COLUMN, INDEX_QUALIFIER, rowKey.get());
context.write(tableName, put);
}
}
}
@Override
protected void setup(Context context) throws IOException, InterruptedException {
Configuration configuration = context.getConfiguration();
String tableName = configuration.get("index.tablename");
String[] fields = configuration.getStrings("index.fields");
String familyName = configuration.get("index.familyname");
family = Bytes.toBytes(familyName);
indexes = new TreeMap<>(Bytes.BYTES_COMPARATOR);
for (String field : fields) {
// if the table is "people" and the field to index is "email", then the
// index table will be called "people-email"
indexes.put(Bytes.toBytes(field),
new ImmutableBytesWritable(Bytes.toBytes(tableName + "-" + field)));
}
}
}
/**
* Job configuration.
*/
public static Job configureJob(Configuration conf, String[] args) throws IOException {
String tableName = args[0];
String columnFamily = args[1];
System.out.println("****" + tableName);
conf.set(TableInputFormat.SCAN, TableMapReduceUtil.convertScanToString(new Scan()));
conf.set(TableInputFormat.INPUT_TABLE, tableName);
conf.set("index.tablename", tableName);
conf.set("index.familyname", columnFamily);
String[] fields = new String[args.length - 2];
System.arraycopy(args, 2, fields, 0, fields.length);
conf.setStrings("index.fields", fields);
Job job = new Job(conf, tableName);
job.setJarByClass(IndexBuilder.class);
job.setMapperClass(Map.class);
job.setNumReduceTasks(0);
job.setInputFormatClass(TableInputFormat.class);
job.setOutputFormatClass(MultiTableOutputFormat.class);
return job;
}
@Override
public int run(String[] args) throws Exception {
Configuration conf = HBaseConfiguration.create(getConf());
if (args.length < 3) {
System.err.println("Only " + args.length + " arguments supplied, required: 3");
System.err.println("Usage: IndexBuilder [ ...]");
System.exit(-1);
}
Job job = configureJob(conf, args);
return (job.waitForCompletion(true) ? 0 : 1);
}
public static void main(String[] args) throws Exception {
int result = ToolRunner.run(HBaseConfiguration.create(), new IndexBuilder(), args);
System.exit(result);
}
}