MapReduce with Cassandra - Beginning Apache Cassandra Development - page 123

// set update CQL and row key
job.getConfiguration().set("row_key",

"key");

String query = "UPDATE " +
KEYSPACE_NAME + "." + COLUMN_FAMILY + " SET
count = ? ";

CqlConfigHelper.setOutputCql(job.getConfiguration(),
query);
//set cql outputformat class

job.setOutputFormatClass(CqlOutputFormat.class);

3. The CQL3-based aggregator is:

public static class TweetCQLAggregator
extends
org.apache.hadoop.mapreduce.Reducer<Text,
IntWritable, Map<String,ByteBuffer>,
List<ByteBuffer>>
{

private static Map<String,ByteBuffer>
keys = new HashMap<>();

/* (non-Javadoc)

* @see
org.apache.hadoop.mapreduce.Reducer#reduce(KEYIN,
java.lang.Iterable,org.apache.hadoop.mapreduce.Reducer.Context)
*/
public void reduce(Text word,
Iterable<IntWritable> values, Context
context) throws IOException,
InterruptedException

{

int sum = 0;
for (IntWritable val : values)
sum += val.get();