1 /** 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 package org.apache.hadoop.hbase.mapreduce; 19 20 import java.io.IOException; 21 import java.util.ArrayList; 22 import java.util.List; 23 24 import org.apache.hadoop.hbase.classification.InterfaceAudience; 25 import org.apache.hadoop.hbase.classification.InterfaceStability; 26 import org.apache.hadoop.conf.Configurable; 27 import org.apache.hadoop.conf.Configuration; 28 import org.apache.hadoop.hbase.client.Scan; 29 30 /** 31 * Convert HBase tabular data from multiple scanners into a format that 32 * is consumable by Map/Reduce. 33 * 34 * <p> 35 * Usage example 36 * </p> 37 * 38 * <pre> 39 * List<Scan> scans = new ArrayList<Scan>(); 40 * 41 * Scan scan1 = new Scan(); 42 * scan1.setStartRow(firstRow1); 43 * scan1.setStopRow(lastRow1); 44 * scan1.setAttribute(Scan.SCAN_ATTRIBUTES_TABLE_NAME, table1); 45 * scans.add(scan1); 46 * 47 * Scan scan2 = new Scan(); 48 * scan2.setStartRow(firstRow2); 49 * scan2.setStopRow(lastRow2); 50 * scan1.setAttribute(Scan.SCAN_ATTRIBUTES_TABLE_NAME, table2); 51 * scans.add(scan2); 52 * 53 * TableMapReduceUtil.initTableMapperJob(scans, TableMapper.class, Text.class, 54 * IntWritable.class, job); 55 * </pre> 56 */ 57 @InterfaceAudience.Public 58 @InterfaceStability.Evolving 59 public class MultiTableInputFormat extends MultiTableInputFormatBase implements 60 Configurable { 61 62 /** Job parameter that specifies the scan list. */ 63 public static final String SCANS = "hbase.mapreduce.scans"; 64 65 /** The configuration. */ 66 private Configuration conf = null; 67 68 /** 69 * Returns the current configuration. 70 * 71 * @return The current configuration. 72 * @see org.apache.hadoop.conf.Configurable#getConf() 73 */ 74 @Override 75 public Configuration getConf() { 76 return conf; 77 } 78 79 /** 80 * Sets the configuration. This is used to set the details for the tables to 81 * be scanned. 82 * 83 * @param configuration The configuration to set. 84 * @see org.apache.hadoop.conf.Configurable#setConf( 85 * org.apache.hadoop.conf.Configuration) 86 */ 87 @Override 88 public void setConf(Configuration configuration) { 89 this.conf = configuration; 90 String[] rawScans = conf.getStrings(SCANS); 91 if (rawScans.length <= 0) { 92 throw new IllegalArgumentException("There must be at least 1 scan configuration set to : " 93 + SCANS); 94 } 95 List<Scan> scans = new ArrayList<Scan>(); 96 97 for (int i = 0; i < rawScans.length; i++) { 98 try { 99 scans.add(TableMapReduceUtil.convertStringToScan(rawScans[i])); 100 } catch (IOException e) { 101 throw new RuntimeException("Failed to convert Scan : " + rawScans[i] + " to string", e); 102 } 103 } 104 this.setScans(scans); 105 } 106 }