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/*
 * 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
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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.*;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.mapreduce.*;

/**
 * The CqlOutputFormat acts as a Hadoop-specific
 * OutputFormat that allows reduce tasks to store keys (and corresponding
 * bound variable values) as CQL rows (and respective columns) in a given
 * table.
 *
 * 

* 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 CqlConfigHelper#setOutputCql} 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. *

* *

* 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. *

*/ public class CqlOutputFormat extends OutputFormat, List> implements org.apache.hadoop.mapred.OutputFormat, List> { public static final String BATCH_THRESHOLD = "mapreduce.output.columnfamilyoutputformat.batch.threshold"; public static final String QUEUE_SIZE = "mapreduce.output.columnfamilyoutputformat.queue.size"; /** * Check for validity of the output-specification for the job. * * @param context * information about the job */ public void checkOutputSpecs(JobContext context) { checkOutputSpecs(HadoopCompat.getConfiguration(context)); } protected void checkOutputSpecs(Configuration conf) { if (ConfigHelper.getOutputKeyspace(conf) == null) throw new UnsupportedOperationException("You must set the keyspace with setOutputKeyspace()"); if (ConfigHelper.getOutputPartitioner(conf) == null) throw new UnsupportedOperationException("You must set the output partitioner to the one used by your Cassandra cluster"); if (ConfigHelper.getOutputInitialAddress(conf) == null) throw new UnsupportedOperationException("You must set the initial output address to a Cassandra node"); } /** Fills the deprecated OutputFormat interface for streaming. */ @Deprecated public void checkOutputSpecs(org.apache.hadoop.fs.FileSystem filesystem, org.apache.hadoop.mapred.JobConf job) throws IOException { checkOutputSpecs(job); } /** * The OutputCommitter for this format does not write any data to the DFS. * * @param context * the task context * @return an output committer * @throws IOException * @throws InterruptedException */ public OutputCommitter getOutputCommitter(TaskAttemptContext context) throws IOException, InterruptedException { return new NullOutputCommitter(); } /** 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, 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); } /** * An {@link OutputCommitter} that does nothing. */ private static class NullOutputCommitter extends OutputCommitter { public void abortTask(TaskAttemptContext taskContext) { } public void cleanupJob(JobContext jobContext) { } public void commitTask(TaskAttemptContext taskContext) { } public boolean needsTaskCommit(TaskAttemptContext taskContext) { return false; } public void setupJob(JobContext jobContext) { } public void setupTask(TaskAttemptContext taskContext) { } } }




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