Exampe of Storing User and Friends Information in Accumulo

This example shows one way to store user and friend information in one Accumulo table. Each friend category becomes a Column Family and each friend's user id becomes a Column Qualifier. After the inserts a small query is run to loop over old friends.

package com.codebits.accumulo;

import java.io.IOException;
import java.util.Iterator;
import java.util.Map;

import org.apache.accumulo.core.client.AccumuloException;
import org.apache.accumulo.core.client.AccumuloSecurityException;
import org.apache.accumulo.core.client.BatchWriter;
import org.apache.accumulo.core.client.Connector;
import org.apache.accumulo.core.client.Instance;
import org.apache.accumulo.core.client.Scanner;
import org.apache.accumulo.core.client.TableExistsException;
import org.apache.accumulo.core.client.TableNotFoundException;
import org.apache.accumulo.core.client.mock.MockInstance;
import org.apache.accumulo.core.data.Key;
import org.apache.accumulo.core.data.Mutation;
import org.apache.accumulo.core.data.Range;
import org.apache.accumulo.core.data.Value;
import org.apache.accumulo.core.security.Authorizations;
import org.apache.hadoop.io.Text;

public class UserAndFriendsDriver {

  public static void main(String[] args) throws IOException, AccumuloException, AccumuloSecurityException, TableExistsException, TableNotFoundException {
    Instance mock = new MockInstance("development");
    Connector connector = mock.getConnector("root", "password".getBytes());
    connector.tableOperations().create("TABLEA");

    BatchWriter wr = connector.createBatchWriter("TABLEA", 10000000, 10000, 5);
    Mutation m = new Mutation(new Text("john"));
    m.put("info:name", "", "john henry");
    m.put("info:gender", "", "male");
    m.put("friend:old", "mark", "");
    wr.addMutation(m);
    m = new Mutation(new Text("mary"));
    m.put("info:name", "", "mark wiggins");
    m.put("info:gender", "", "female");
    m.put("friend:new", "mark", "");
    m.put("friend:old", "lucas", "");
    m.put("friend:old", "aaron", "");
    wr.addMutation(m);
    wr.close();

    Scanner scanner = connector.createScanner("TABLEA", new Authorizations());
    scanner.setRange(new Range("a", "z"));
    scanner.fetchColumnFamily(new Text("friend:old"));
    Iterator<Map.Entry<Key, Value>> iterator = scanner.iterator();
    while (iterator.hasNext()) {
      Map.Entry<Key, Value> entry = iterator.next();
      Key key = entry.getKey();
      System.out.println("Old Friends: " + key.getRow() + " -> " + key.getColumnQualifier());
    }
  }
}