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| <div class="subTitle">org.apache.hawq.pxf.plugins.hdfs</div> |
| <h2 title="Class ChunkRecordReader" class="title">Class ChunkRecordReader</h2> |
| </div> |
| <div class="contentContainer"> |
| <ul class="inheritance"> |
| <li>java.lang.Object</li> |
| <li> |
| <ul class="inheritance"> |
| <li>org.apache.hawq.pxf.plugins.hdfs.ChunkRecordReader</li> |
| </ul> |
| </li> |
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| <div class="description"> |
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| <dl> |
| <dt>All Implemented Interfaces:</dt> |
| <dd>org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.LongWritable,<a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkWritable.html" title="class in org.apache.hawq.pxf.plugins.hdfs">ChunkWritable</a>></dd> |
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| <br> |
| <pre>public class <span class="typeNameLabel">ChunkRecordReader</span> |
| extends java.lang.Object |
| implements org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.LongWritable,<a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkWritable.html" title="class in org.apache.hawq.pxf.plugins.hdfs">ChunkWritable</a>></pre> |
| <div class="block">ChunkRecordReader is designed for fast reading of a file split. The idea is |
| to bring chunks of data instead of single records. The chunks contain many |
| records and the chunk end is not aligned on a record boundary. The size of |
| the chunk is a class hardcoded parameter - CHUNK_SIZE. This behaviour sets |
| this reader apart from the other readers which will fetch one record and stop |
| when reaching a record delimiter.</div> |
| </li> |
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| <tr> |
| <th class="colOne" scope="col">Constructor and Description</th> |
| </tr> |
| <tr class="altColor"> |
| <td class="colOne"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkRecordReader.html#ChunkRecordReader-org.apache.hadoop.conf.Configuration-org.apache.hadoop.mapred.FileSplit-">ChunkRecordReader</a></span>(org.apache.hadoop.conf.Configuration job, |
| org.apache.hadoop.mapred.FileSplit split)</code> |
| <div class="block">Constructs a ChunkRecordReader instance.</div> |
| </td> |
| </tr> |
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| <tr> |
| <th class="colFirst" scope="col">Modifier and Type</th> |
| <th class="colLast" scope="col">Method and Description</th> |
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| <tr id="i0" class="altColor"> |
| <td class="colFirst"><code>void</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkRecordReader.html#close--">close</a></span>()</code> |
| <div class="block">Closes the input stream.</div> |
| </td> |
| </tr> |
| <tr id="i1" class="rowColor"> |
| <td class="colFirst"><code>org.apache.hadoop.io.LongWritable</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkRecordReader.html#createKey--">createKey</a></span>()</code> |
| <div class="block">Used by the client of this class to create the 'key' output parameter for |
| next() method.</div> |
| </td> |
| </tr> |
| <tr id="i2" class="altColor"> |
| <td class="colFirst"><code><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkWritable.html" title="class in org.apache.hawq.pxf.plugins.hdfs">ChunkWritable</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkRecordReader.html#createValue--">createValue</a></span>()</code> |
| <div class="block">Used by the client of this class to create the 'value' output parameter |
| for next() method.</div> |
| </td> |
| </tr> |
| <tr id="i3" class="rowColor"> |
| <td class="colFirst"><code>long</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkRecordReader.html#getPos--">getPos</a></span>()</code> |
| <div class="block">Returns the position of the unread tail of the file</div> |
| </td> |
| </tr> |
| <tr id="i4" class="altColor"> |
| <td class="colFirst"><code>float</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkRecordReader.html#getProgress--">getProgress</a></span>()</code> |
| <div class="block">Gets the progress within the split.</div> |
| </td> |
| </tr> |
| <tr id="i5" class="rowColor"> |
| <td class="colFirst"><code>org.apache.hadoop.hdfs.DFSInputStream.ReadStatistics</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkRecordReader.html#getReadStatistics--">getReadStatistics</a></span>()</code> |
| <div class="block">Returns statistics of the input stream's read operation: total bytes |
| read, bytes read locally, bytes read in short-circuit (directly from file |
| descriptor).</div> |
| </td> |
| </tr> |
| <tr id="i6" class="altColor"> |
| <td class="colFirst"><code>boolean</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkRecordReader.html#next-org.apache.hadoop.io.LongWritable-org.apache.hawq.pxf.plugins.hdfs.ChunkWritable-">next</a></span>(org.apache.hadoop.io.LongWritable key, |
| <a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkWritable.html" title="class in org.apache.hawq.pxf.plugins.hdfs">ChunkWritable</a> value)</code> |
| <div class="block">Fetches the next data chunk from the file split.</div> |
| </td> |
| </tr> |
| </table> |
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| <!-- --> |
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| <h3>Methods inherited from class java.lang.Object</h3> |
| <code>clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait</code></li> |
| </ul> |
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| <h3>Constructor Detail</h3> |
| <a name="ChunkRecordReader-org.apache.hadoop.conf.Configuration-org.apache.hadoop.mapred.FileSplit-"> |
| <!-- --> |
| </a> |
| <ul class="blockListLast"> |
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| <h4>ChunkRecordReader</h4> |
| <pre>public ChunkRecordReader(org.apache.hadoop.conf.Configuration job, |
| org.apache.hadoop.mapred.FileSplit split) |
| throws java.io.IOException</pre> |
| <div class="block">Constructs a ChunkRecordReader instance.</div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>job</code> - the job configuration</dd> |
| <dd><code>split</code> - contains the file name, begin byte of the split and the |
| bytes length</dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code>java.io.IOException</code> - if an I/O error occurs when accessing the file or |
| creating input stream to read from it</dd> |
| </dl> |
| </li> |
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| <a name="getReadStatistics--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>getReadStatistics</h4> |
| <pre>public org.apache.hadoop.hdfs.DFSInputStream.ReadStatistics getReadStatistics()</pre> |
| <div class="block">Returns statistics of the input stream's read operation: total bytes |
| read, bytes read locally, bytes read in short-circuit (directly from file |
| descriptor).</div> |
| <dl> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>an instance of ReadStatistics class</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="createKey--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
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| <h4>createKey</h4> |
| <pre>public org.apache.hadoop.io.LongWritable createKey()</pre> |
| <div class="block">Used by the client of this class to create the 'key' output parameter for |
| next() method.</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code>createKey</code> in interface <code>org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.LongWritable,<a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkWritable.html" title="class in org.apache.hawq.pxf.plugins.hdfs">ChunkWritable</a>></code></dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>an instance of LongWritable</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="createValue--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>createValue</h4> |
| <pre>public <a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkWritable.html" title="class in org.apache.hawq.pxf.plugins.hdfs">ChunkWritable</a> createValue()</pre> |
| <div class="block">Used by the client of this class to create the 'value' output parameter |
| for next() method.</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code>createValue</code> in interface <code>org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.LongWritable,<a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkWritable.html" title="class in org.apache.hawq.pxf.plugins.hdfs">ChunkWritable</a>></code></dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>an instance of ChunkWritable</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="next-org.apache.hadoop.io.LongWritable-org.apache.hawq.pxf.plugins.hdfs.ChunkWritable-"> |
| <!-- --> |
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| <h4>next</h4> |
| <pre>public boolean next(org.apache.hadoop.io.LongWritable key, |
| <a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkWritable.html" title="class in org.apache.hawq.pxf.plugins.hdfs">ChunkWritable</a> value) |
| throws java.io.IOException</pre> |
| <div class="block">Fetches the next data chunk from the file split. The size of the chunk is |
| a class hardcoded parameter - CHUNK_SIZE. This behaviour sets this reader |
| apart from the other readers which will fetch one record and stop when |
| reaching a record delimiter.</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code>next</code> in interface <code>org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.LongWritable,<a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkWritable.html" title="class in org.apache.hawq.pxf.plugins.hdfs">ChunkWritable</a>></code></dd> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>key</code> - - output parameter. When method returns will contain the key - |
| the number of the start byte of the chunk</dd> |
| <dd><code>value</code> - - output parameter. When method returns will contain the |
| value - the chunk, a byte array inside the ChunkWritable |
| instance</dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>false - when end of split was reached</dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code>java.io.IOException</code> - if an I/O error occurred while reading the next chunk |
| or line</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="getProgress--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>getProgress</h4> |
| <pre>public float getProgress() |
| throws java.io.IOException</pre> |
| <div class="block">Gets the progress within the split.</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code>getProgress</code> in interface <code>org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.LongWritable,<a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkWritable.html" title="class in org.apache.hawq.pxf.plugins.hdfs">ChunkWritable</a>></code></dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code>java.io.IOException</code></dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="getPos--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>getPos</h4> |
| <pre>public long getPos() |
| throws java.io.IOException</pre> |
| <div class="block">Returns the position of the unread tail of the file</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code>getPos</code> in interface <code>org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.LongWritable,<a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkWritable.html" title="class in org.apache.hawq.pxf.plugins.hdfs">ChunkWritable</a>></code></dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>pos - start byte of the unread tail of the file</dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code>java.io.IOException</code></dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="close--"> |
| <!-- --> |
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| <h4>close</h4> |
| <pre>public void close() |
| throws java.io.IOException</pre> |
| <div class="block">Closes the input stream.</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code>close</code> in interface <code>org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.LongWritable,<a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/ChunkWritable.html" title="class in org.apache.hawq.pxf.plugins.hdfs">ChunkWritable</a>></code></dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code>java.io.IOException</code></dd> |
| </dl> |
| </li> |
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| </li> |
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