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Custom TableInputFormat not working correctly
edward choi 2011-06-19, 15:49
Hi,

I have implemented a custom TableInputFormat.
I call it TableInputFormatMapPerRow and that is exactly what it does.
The getSplits() of my custom TableInputFormat creates a TableSplit for each
row in the HBase.
But when I actually run an application with my custom TableInputFormat,
there are not enough map tasks than there should be.
I really don't know what I am doing wrong.
Any suggestions please?
Below is my TableInputFormatMapPerRow.java

Ed

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/**
 * Copyright 2007 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 java.util.ArrayList;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.InputFormat;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.util.StringUtils;

import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.filter.KeyOnlyFilter;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableInputFormatBase;
import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
import org.apache.hadoop.hbase.util.Bytes;

/**
 * Convert HBase tabular data into a format that is consumable by
Map/Reduce.
 */
public class TableInputFormatMapPerRow extends
InputFormat<ImmutableBytesWritable, Result>
implements Configurable {

  private final Log LOG LogFactory.getLog(TableInputFormatMapPerRow.class);

  /** Job parameter that specifies the input table. */
  public static final String INPUT_TABLE = "hbase.mapreduce.inputtable";
  /** Base-64 encoded scanner. All other SCAN_ confs are ignored if this is
specified.
   * See {@link TableMapReduceUtil#convertScanToString(Scan)} for more
details.
   */
  public static final String SCAN = "hbase.mapreduce.scan";
  /** Column Family to Scan */
  public static final String SCAN_COLUMN_FAMILY "hbase.mapreduce.scan.column.family";
  /** Space delimited list of columns to scan. */
  public static final String SCAN_COLUMNS = "hbase.mapreduce.scan.columns";
  /** The timestamp used to filter columns with a specific timestamp. */
  public static final String SCAN_TIMESTAMP "hbase.mapreduce.scan.timestamp";
  /** The starting timestamp used to filter columns with a specific range of
versions. */
  public static final String SCAN_TIMERANGE_START "hbase.mapreduce.scan.timerange.start";
  /** The ending timestamp used to filter columns with a specific range of
versions. */
  public static final String SCAN_TIMERANGE_END "hbase.mapreduce.scan.timerange.end";
  /** The maximum number of version to return. */
  public static final String SCAN_MAXVERSIONS "hbase.mapreduce.scan.maxversions";
  /** Set to false to disable server-side caching of blocks for this scan.
*/
  public static final String SCAN_CACHEBLOCKS "hbase.mapreduce.scan.cacheblocks";
  /** The number of rows for caching that will be passed to scanners. */
  public static final String SCAN_CACHEDROWS "hbase.mapreduce.scan.cachedrows";

  /** The configuration. */
  private Configuration conf = null;
  private HTable table = null;
  private Scan scan = null;
  private TableRecordReader tableRecordReader = null;

  /**
   * Returns the current configuration.
   *
   * @return The current configuration.
   * @see org.apache.hadoop.conf.Configurable#getConf()
   */
  @Override
  public Configuration getConf() {
    return conf;
  }

  /**
   * Sets the configuration. This is used to set the details for the table
to
   * be scanned.
   *
   * @param configuration  The configuration to set.
   * @see org.apache.hadoop.conf.Configurable#setConf(
   *   org.apache.hadoop.conf.Configuration)
   */
  @Override
  public void setConf(Configuration configuration) {
    this.conf = configuration;
    String tableName = conf.get(INPUT_TABLE);
    /*
    try {
      setHTable(new HTable(new Configuration(conf), tableName));
    } catch (Exception e) {
      LOG.error(StringUtils.stringifyException(e));
    }
    */
    try
    {
        this.table = new HTable(new Configuration(conf), tableName);
    }
    catch (Exception e)
    {
        LOG.error(StringUtils.stringifyException(e));
    }

    Scan scan = null;

    if (conf.get(SCAN) != null) {
      try {
        scan = TableMapReduceUtil.convertStringToScan(conf.get(SCAN));
      } catch (IOException e) {
        LOG.error("An error occurred.", e);
      }
    } else {
      try {
        scan = new Scan();

        if (conf.get(SCAN_COLUMNS) != null) {
          scan.addColumns(conf.get(SCAN_COLUMNS));
        }

        if (conf.get(SCAN_COLUMN_FAMILY) != null) {
          scan.addFamily(Bytes.toBytes(conf.get(SCAN_COLUMN_FAMILY)));
        }

        if (con