Hbase建索引分析

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Hbase

1. Hbase的一个例子，IndexBuilde

r.建索引.代码及解析如下：

/**
 * 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.frame.base.hbase.hadoop.hbase;

import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.HashMap;

import org.apache.hadoop.conf.Configuration;
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.mapreduce.MultiTableOutputFormat;
import org.apache.hadoop.hbase.mapreduce.TableInputFormat;
import org.apache.hadoop.hbase.util.Base64;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.util.GenericOptionsParser;

/**
 * 基本列值，创建索引.
 */

/**
 * 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:
 * [list]
 * <li>Using TableInputFormat and TableMapReduceUtil to use an HTable as input
 * to a map/reduce job.</li>
 * [*]Passing values from main method to children via the configuration.

 * <li>Using MultiTableOutputFormat to output to multiple tables from a
 * map/reduce job.</li>
 * [*]A real use case of building a secondary index over a table.

 * [/list]
 *
 * <h3>Usage</h3>
 *
 * 
 * Modify ${HADOOP_HOME}/conf/hadoop-env.sh to include the hbase jar, the
 * zookeeper jar, the examples output directory, and the hbase conf directory in
 * HADOOP_CLASSPATH, and then run
 * <tt>[b]bin/hadoop org.apache.hadoop.hbase.mapreduce.IndexBuilder TABLE_NAME COLUMN_FAMILY ATTR [ATTR ...][/b]</tt>
 * 

 *
 * 
 * To run with the sample data provided in index-builder-setup.rb, use the
 * arguments [b]<tt>people attributes name email phone</tt>[/b].
 * 

 *
 * 
 * This code was written against HBase 0.21 trunk.
 * 

 */
public class IndexBuilder {
  /** 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<ImmutableBytesWritable, Result, ImmutableBytesWritable, Writable> {
    private byte[] family;
    private HashMap<byte[], ImmutableBytesWritable> indexes;

    @Override
    protected void map(ImmutableBytesWritable rowKey, Result result, Context context)
        throws IOException, InterruptedException {
      for(java.util.Map.Entry<byte[], ImmutableBytesWritable> 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.add(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 HashMap<byte[], ImmutableBytesWritable>();
      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, 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];
    for(int i = 0; i < fields.length; i++) {
      fields[i] = args[i + 2];
    }
    conf.setStrings("index.fields", fields);
    //conf.set("index.familyname", "attributes");
    Job job = new Job(conf, tableName);
    job.setJarByClass(IndexBuilder.class);
    job.setMapperClass(Map.class);
    job.setNumReduceTasks(0);//mapred.reduce.tasks，设置为0表示不需要reduce.
    job.setInputFormatClass(TableInputFormat.class);
    job.setOutputFormatClass(MultiTableOutputFormat.class);
    return job;
  }

  /**
   * 把scan转为String类型
   * @param scan
   * @return
   * @throws IOException
   */
  private static String convertScanToString(Scan scan) throws IOException{
	  ByteArrayOutputStream out = new ByteArrayOutputStream();
	  DataOutputStream dos = new DataOutputStream(out);
	  scan.write(dos);
	  return Base64.encodeBytes(out.toByteArray());
  }

  public static void main(String[] args) throws Exception {
    Configuration conf = HBaseConfiguration.create();
    String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
    if(otherArgs.length < 3) {
      System.err.println("Only " + otherArgs.length + " arguments supplied, required: 3");
      System.err.println("Usage: IndexBuilder <TABLE_NAME> <COLUMN_FAMILY> <ATTR> [<ATTR> ...]");
      System.exit(-1);
    }
    Job job = configureJob(conf, otherArgs);
    System.exit(job.waitForCompletion(true) ? 0 : 1);
  }
}

首先需要在Hbase里面建一张表，然后放入一点测试数据，数据结构如下:

/**
   原始表
 * table1
 *          family1:column1   family1:column2
 * key1          value1          value11
 * key2          value2          value22
 *
   索引表
 * table1-column1
 *
 *          INDEX:ROW
 * value1      key1
 * value2      key2
 *
 */

这是我们预想的，执行命令:

bin/hadoop IndexBuilder.jar IndexBuilder 'table1' 'family1' 'column1'

指定参数执行建立Hbase索引表，当然这是一对一的索引建立方法，如果column1可能为相同的，就不能这么建索引了。
不过可以采用:

  value1_key1  empty
  value2_key2  empty

采用前缀的方式，这样Hbase进行搜索的时候，先根据value1得到他的key列表，然后再通过key列表搜索值.

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把xls的数据导到Hbase | Hadoop WordCount进阶

2011-11-07 15:45
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评论(9)
分类:编程语言
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9 楼 wubo2qml 2014-02-20

长见识了，原来这就是给hbase建立索引啊！

8 楼 a123159521 2013-10-30

shenxiaoming77 写道

指定参数执行建立Hbase索引表，当然这是一对一的索引建立方法，如果column1可能为相同的，就不能这么建索引了。
不过可以采用:

1.value1_key1 empty
2.value2_key2 empty

你好，请问下在colemn出现相同值得情况下对该列建立索引表，不知道该怎么设置，上面的
1.value1_key1 empty
2.value2_key2 empty
具体表示什么意思？该怎么设置？请指点一下，谢谢

好久没来了，这个其实很简单，和HashMap的实现一致。
If key is unique, then <key, value> <key1,value1>
if key is not unique, them <key, valueList>

via key to get valueList, then scan the list to get value.

of cause, the key's generator is decide by your designer.

7 楼 shenxiaoming77 2013-08-09

6 楼 dinghongkai123 2013-06-05

你好，索引表建立完，怎么查询？？

5 楼 571023881 2013-05-18

a123159521 写道

571023881 写道

你好，这个索引在运行以后显示的结果难道只有显示一个表名么？怎么确切知道索引已经建好了

索引表建好后，有表名，表内还有索引数据

在eclipse里运行后输出一个表名，那么表内的索引数据怎么看到？在终端里使用shell命令倒是可以看到索引表的全部数据，终端可以显示“列族属性+索引的rowkey”

4 楼 a123159521 2013-05-15

571023881 写道

你好，这个索引在运行以后显示的结果难道只有显示一个表名么？怎么确切知道索引已经建好了

索引表建好后，有表名，表内还有索引数据

3 楼 571023881 2013-05-10

你好，这个索引在运行以后显示的结果难道只有显示一个表名么？怎么确切知道索引已经建好了

2 楼 a123159521 2011-11-17

when you run this job,you should be create table first. or right,you will be get error below

anbo724 写道

你好为什么我使用你的代码在运行的时候，出现问题。

11/11/17 15:01:19 WARN client.HConnectionManager$HConnectionImplementation: Encountered problems when prefetch META table: org.apache.hadoop.hbase.TableNotFoundException: Cannot find row in .META. for table: hero-name, row=hero-name,,99999999999999at org.apache.hadoop.hbase.client.MetaScanner.metaScan(MetaScanner.java:136)at org.apache.hadoop.hbase.client.MetaScanner.metaScan(MetaScanner.java:95)at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.prefetchRegionCache(HConnectionManager.java:648)at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegionInMeta(HConnectionManager.java:702)at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegion(HConnectionManager.java:593)at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegion(HConnectionManager.java:558)at org.apache.hadoop.hbase.client.HTable.<init>(HTable.java:172)at org.apache.hadoop.hbase.mapreduce.MultiTableOutputFormat$MultiTableRecordWriter.getTable(MultiTableOutputFormat.java:101)at org.apache.hadoop.hbase.mapreduce.MultiTableOutputFormat$MultiTableRecordWriter.write(MultiTableOutputFormat.java:127)at org.apache.hadoop.hbase.mapreduce.MultiTableOutputFormat$MultiTableRecordWriter.write(MultiTableOutputFormat.java:68)at org.apache.hadoop.mapred.MapTask$NewDirectOutputCollector.write(MapTask.java:498)at org.apache.hadoop.mapreduce.TaskInputOutputContext.write(TaskInputOutputContext.java:80)at an.index.hbase.IndexBuilder$Map.map(IndexBuilder.java:107)at an.index.hbase.IndexBuilder$Map.map(IndexBuilder.java:1)at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:621)at org.apache.hadoop.mapred.MapTask.run(MapTask.java:305)at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:177)

其中hero是表名 name是对应要建立的索引的列

1 楼 anbo724 2011-11-17

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