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SequenceFileInputFormat and SequenceFileKeyRecordReader for enabling Hive to access data stored in a sequence file's key
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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 | |
* limitations under the License. | |
*/ | |
package com.mycompany; | |
import java.io.IOException; | |
import org.apache.hadoop.fs.FileStatus; | |
import org.apache.hadoop.fs.FileSystem; | |
import org.apache.hadoop.fs.Path; | |
import org.apache.hadoop.io.SequenceFile; | |
import org.apache.hadoop.io.MapFile; | |
import org.apache.hadoop.mapred.FileInputFormat; | |
import org.apache.hadoop.mapred.FileSplit; | |
import org.apache.hadoop.mapred.InputSplit; | |
import org.apache.hadoop.mapred.JobConf; | |
import org.apache.hadoop.mapred.RecordReader; | |
import org.apache.hadoop.mapred.Reporter; | |
public class SequenceFileKeyInputFormat<K, V> extends FileInputFormat<K, V> { | |
public SequenceFileKeyInputFormat() { | |
setMinSplitSize(SequenceFile.SYNC_INTERVAL); | |
} | |
@Override | |
protected FileStatus[] listStatus(JobConf job) throws IOException { | |
FileStatus[] files = super.listStatus(job); | |
for (int i = 0; i < files.length; i++) { | |
FileStatus file = files[i]; | |
if (file.isDir()) { // it's a MapFile | |
Path dataFile = new Path(file.getPath(), MapFile.DATA_FILE_NAME); | |
FileSystem fs = file.getPath().getFileSystem(job); | |
// use the data file | |
files[i] = fs.getFileStatus(dataFile); | |
} | |
} | |
return files; | |
} | |
public RecordReader<K, V> getRecordReader(InputSplit split, | |
JobConf job, Reporter reporter) | |
throws IOException { | |
reporter.setStatus(split.toString()); | |
return new SequenceFileKeyRecordReader<V, K>(job, (FileSplit) split); | |
} | |
} |
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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 | |
* limitations under the License. | |
*/ | |
package com.mycompany; | |
import java.io.IOException; | |
import org.apache.hadoop.conf.Configuration; | |
import org.apache.hadoop.fs.FileSystem; | |
import org.apache.hadoop.fs.Path; | |
import org.apache.hadoop.io.*; | |
import org.apache.hadoop.mapred.FileSplit; | |
import org.apache.hadoop.mapred.RecordReader; | |
import org.apache.hadoop.util.ReflectionUtils; | |
public class SequenceFileKeyRecordReader<K, V> implements RecordReader<V, K> { | |
private SequenceFile.Reader in; | |
private long start; | |
private long end; | |
private boolean more = true; | |
protected Configuration conf; | |
public SequenceFileKeyRecordReader(Configuration conf, FileSplit split) | |
throws IOException { | |
Path path = split.getPath(); | |
FileSystem fs = path.getFileSystem(conf); | |
this.in = new SequenceFile.Reader(fs, path, conf); | |
this.end = split.getStart() + split.getLength(); | |
this.conf = conf; | |
if (split.getStart() > in.getPosition()) | |
in.sync(split.getStart()); // sync to start | |
this.start = in.getPosition(); | |
more = start < end; | |
} | |
/** The class of key that must be passed to {@link | |
* #next(Object, Object)}.. */ | |
public Class getKeyClass() { return in.getValueClass(); } | |
/** The class of value that must be passed to {@link | |
* #next(Object, Object)}.. */ | |
public Class getValueClass() { return in.getKeyClass(); } | |
@SuppressWarnings("unchecked") | |
public V createKey() { | |
return (V) ReflectionUtils.newInstance(getKeyClass(), conf); | |
} | |
@SuppressWarnings("unchecked") | |
public K createValue() { | |
return (K) ReflectionUtils.newInstance(getValueClass(), conf); | |
} | |
public synchronized boolean next(V key, K value) throws IOException { | |
if (!more) return false; | |
long pos = in.getPosition(); | |
boolean remaining = (in.next(value) != null); | |
if (remaining) { | |
getCurrentValue(key); | |
} | |
if (pos >= end && in.syncSeen()) { | |
more = false; | |
} else { | |
more = remaining; | |
} | |
return more; | |
} | |
protected synchronized boolean next(K key) | |
throws IOException { | |
if (!more) return false; | |
long pos = in.getPosition(); | |
boolean remaining = (in.next(key) != null); | |
if (pos >= end && in.syncSeen()) { | |
more = false; | |
} else { | |
more = remaining; | |
} | |
return more; | |
} | |
protected synchronized void getCurrentValue(V value) | |
throws IOException { | |
in.getCurrentValue(value); | |
} | |
/** | |
* Return the progress within the input split | |
* @return 0.0 to 1.0 of the input byte range | |
*/ | |
public float getProgress() throws IOException { | |
if (end == start) { | |
return 0.0f; | |
} else { | |
return Math.min(1.0f, (in.getPosition() - start) / (float)(end - start)); | |
} | |
} | |
public synchronized long getPos() throws IOException { | |
return in.getPosition(); | |
} | |
protected synchronized void seek(long pos) throws IOException { | |
in.seek(pos); | |
} | |
public synchronized void close() throws IOException { in.close(); } | |
} |
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