/*
* 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.cassandra.hadoop.cql3;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Map;
import org.apache.cassandra.hadoop.HadoopCompat;
import org.apache.cassandra.hadoop.AbstractColumnFamilyInputFormat;
import org.apache.cassandra.hadoop.ReporterWrapper;
import org.apache.hadoop.mapred.InputSplit;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.RecordReader;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.TaskAttemptID;
import com.datastax.driver.core.Row;
/**
* Hadoop InputFormat allowing map/reduce against Cassandra rows within one ColumnFamily.
*
* At minimum, you need to set the KS and CF in your Hadoop job Configuration.
* The ConfigHelper class is provided to make this
* simple:
* ConfigHelper.setInputColumnFamily
*
* You can also configure the number of rows per InputSplit with
* ConfigHelper.setInputSplitSize. The default split size is 64k rows.
*
* the number of CQL rows per page
* CQLConfigHelper.setInputCQLPageRowSize. The default page row size is 1000. You
* should set it to "as big as possible, but no bigger." It set the LIMIT for the CQL
* query, so you need set it big enough to minimize the network overhead, and also
* not too big to avoid out of memory issue.
*
* other native protocol connection parameters in CqlConfigHelper
*/
public class CqlInputFormat extends AbstractColumnFamilyInputFormat<Long, Row>
{
public RecordReader<Long, Row> getRecordReader(InputSplit split, JobConf jobConf, final Reporter reporter)
throws IOException
{
TaskAttemptContext tac = HadoopCompat.newMapContext(
jobConf,
TaskAttemptID.forName(jobConf.get(MAPRED_TASK_ID)),
null,
null,
null,
new ReporterWrapper(reporter),
null);
CqlRecordReader recordReader = new CqlRecordReader();
recordReader.initialize((org.apache.hadoop.mapreduce.InputSplit)split, tac);
return recordReader;
}
@Override
public org.apache.hadoop.mapreduce.RecordReader<Long, Row> createRecordReader(
org.apache.hadoop.mapreduce.InputSplit arg0, TaskAttemptContext arg1) throws IOException,
InterruptedException
{
return new CqlRecordReader();
}
}