/*
* 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.List;
import java.util.Map;
import org.apache.cassandra.hadoop.AbstractColumnFamilyOutputFormat;
import org.apache.cassandra.hadoop.ColumnFamilyInputFormat;
import org.apache.cassandra.hadoop.ConfigHelper;
import org.apache.cassandra.hadoop.Progressable;
import org.apache.hadoop.mapreduce.*;
/**
* The <code>ColumnFamilyOutputFormat</code> acts as a Hadoop-specific
* OutputFormat that allows reduce tasks to store keys (and corresponding
* binded variable values) as CQL rows (and respective columns) in a given
* ColumnFamily.
*
* <p>
* As is the case with the {@link org.apache.cassandra.hadoop.ColumnFamilyInputFormat},
* you need to set the prepared statement in your
* Hadoop job Configuration. The {@link CqlConfigHelper} class, through its
* {@link ConfigHelper#setOutputPreparedStatement} method, is provided to make this
* simple.
* you need to set the Keyspace. The {@link ConfigHelper} class, through its
* {@link ConfigHelper#setOutputColumnFamily} method, is provided to make this
* simple.
* </p>
*
* <p>
* For the sake of performance, this class employs a lazy write-back caching
* mechanism, where its record writer prepared statement binded variable values
* created based on the reduce's inputs (in a task-specific map), and periodically
* makes the changes official by sending a execution of prepared statement request
* to Cassandra.
* </p>
*/
public class CqlOutputFormat extends AbstractColumnFamilyOutputFormat<Map<String, ByteBuffer>, List<ByteBuffer>>
{
/** Fills the deprecated OutputFormat interface for streaming. */
@Deprecated
public CqlRecordWriter getRecordWriter(org.apache.hadoop.fs.FileSystem filesystem, org.apache.hadoop.mapred.JobConf job, String name, org.apache.hadoop.util.Progressable progress) throws IOException
{
return new CqlRecordWriter(job, new Progressable(progress));
}
/**
* Get the {@link RecordWriter} for the given task.
*
* @param context
* the information about the current task.
* @return a {@link RecordWriter} to write the output for the job.
* @throws IOException
*/
public CqlRecordWriter getRecordWriter(final TaskAttemptContext context) throws IOException, InterruptedException
{
return new CqlRecordWriter(context);
}
}