Prerequisites

  1. Prepare the JAR package of the test program. Assume the package is named mapreduce-examples.jar, and the local storage path is data\resources.
  2. Prepare tables and resources for testing the Unique operation.
    • Create tables:
      create table ss_in(key bigint, value bigint);
create table ss_out(key bigint, value bigint);
    • Add resources:
      add jar data\resources\mapreduce-examples.jar -f;
  3. Use the tunnel command to import the data.
    tunnel upload data ss_in;
    The contents of data file are imported into the table ss_in.
     1,1
 1,1
 2,2
 2,2

Procedure

Run Unique on the odpscmd, as follows:
jar -resources mapreduce-examples.jar -classpath data\resources\mapreduce-examples.jar
com.aliyun.odps.mapred.open.example.Unique ss_in ss_out key;

Expected output

The content of output table ss_out is as follows:
+------------+------------+
| key | value |
+------------+------------+
| 1 | 1 |
| 2 | 2 |
+------------+------------+

Sample code

    package com.aliyun.odps.mapred.open.example;
    import java.io.IOException;
    Import java. util. iterator;
    Import com. aliyun. ODPS. Data. record;
    import com.aliyun.odps.data.TableInfo;
    import com.aliyun.odps.mapred.JobClient;
    import com.aliyun.odps.mapred.MapperBase;
    import com.aliyun.odps.mapred.ReducerBase;
    import com.aliyun.odps.mapred.TaskContext;
    import com.aliyun.odps.mapred.conf.JobConf;
    import com.aliyun.odps.mapred.utils.InputUtils;
    import com.aliyun.odps.mapred.utils.OutputUtils;
    import com.aliyun.odps.mapred.utils.SchemaUtils;
    /**
     * Unique Remove duplicate words
     *
     **/
    public class Unique {
      public static class OutputSchemaMapper extends MapperBase {
        private Record key;
        private Record value;
        @Override
        public void setup(TaskContext context) throws IOException{
          key = context.createMapOutputKeyRecord();
          value = context.createMapOutputValueRecord();
        }
        @Override
        public void map(long recordNum, Record record, TaskContext context)
            Throws ioexception {
          long left = 0;
          long right = 0;
          if (record.getColumnCount() > 0) {
            left = (Long) record.get(0);
            if (record.getColumnCount() > 1) {
              right = (Long) record.get(1);
            }
            key.set(new Object[] { (Long) left, (Long) right });
            value.set(new Object[] { (Long) left, (Long) right });
            context.write(key, value);
          }
        }
      }
      public static class OutputSchemaReducer extends ReducerBase {
        private Record result = null;
        @Override
        public void setup(TaskContext context) throws IOException{
          result = context.createOutputRecord();
        }
        @Override
        public void reduce(Record key,Iterator<Record>values,TaskContext context)
            Throws ioexception {
          result.set(0, key.get(0));
          while(values.hasNext()) {
            Record value = values.next();
            result.set(1, value.get(1));
          }
          context.write(result);
        }
      }
      public static void main(String[] args) throws Exception {
        if (args.length > 3 || args.length < 2) {
          System.err.println("Usage: unique <in> <out> [key|value|all]");
          System.exit(2);
        }
        String ops = "all";
        if (args.length == 3) {
          Ops = ARGs [2];
        }
        /** Reduce input grouping is determined by the settings of the scanner, this parameter if it is not set. */
        /Default is mapoutputkeyschema
        // Key Unique
        if (ops.equals("key")) {
          JobConf job = new JobConf();
          job.setMapperClass(OutputSchemaMapper.class);
          job.setReducerClass(OutputSchemaReducer.class);
          job.setMapOutputKeySchema(SchemaUtils.fromString("key:bigint,value:bigint"));
          job.setMapOutputValueSchema(SchemaUtils.fromString("key:bigint,value:bigint"));
          job.setPartitionColumns(new String[] { "key" });
          job.setOutputKeySortColumns(new String[] { "key", "value" });
          job.setOutputGroupingColumns(new String[] { "key" });
          job.set("tablename2", args[1]);
          job.setNumReduceTasks(1);
          job.setInt("table.counter", 0);
          InputUtils.addTable(TableInfo.builder().tableName(args[0]).build(), job);
          OutputUtils.addTable(TableInfo.builder().tableName(args[1]).build(), job);
          Jobclient. runjob (job );
        }
        // Key&Value Unique
        if (ops.equals("all")) {
          JobConf job = new JobConf();
          job.setMapperClass(OutputSchemaMapper.class);
          job.setReducerClass(OutputSchemaReducer.class);
          job.setMapOutputKeySchema(SchemaUtils.fromString("key:bigint,value:bigint"));
          job.setMapOutputValueSchema(SchemaUtils.fromString("key:bigint,value:bigint"));
          job.setPartitionColumns(new String[] { "key" });
          job.setOutputKeySortColumns(new String[] { "key", "value" });
          job.setOutputGroupingColumns(new String[] { "key", "value" });
          Job. Set ("tablename2", argS [1]);
          job.setNumReduceTasks(1);
          job.setInt("table.counter", 0);
          InputUtils.addTable(TableInfo.builder().tableName(args[0]).build(), job);
          OutputUtils.addTable(TableInfo.builder().tableName(args[1]).build(), job);
          Jobclient. runjob (job );
        }
        // Value Unique
        if (ops.equals("value")) {
          JobConf job = new JobConf();
          job.setMapperClass(OutputSchemaMapper.class);
          job.setReducerClass(OutputSchemaReducer.class);
          job.setMapOutputKeySchema(SchemaUtils.fromString("key:bigint,value:bigint"));
          job.setMapOutputValueSchema(SchemaUtils.fromString("key:bigint,value:bigint"));
          job.setPartitionColumns(new String[] { "value" });
          job.setOutputKeySortColumns(new String[] { "value" });
          job.setOutputGroupingColumns(new String[] { "value" });
          job.set("tablename2", args[1]);-
          job.setNumReduceTasks(1);
          job.setInt("table.counter", 0);
          InputUtils.addTable(TableInfo.builder().tableName(args[0]).build(), job);
          OutputUtils.addTable(TableInfo.builder().tableName(args[1]).build(), job);
          Jobclient. runjob (job );
        }
      }
    }