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  1. PO
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    <p>I think I understand the question... here's what I would do: wrap another RecordReader and buffer the keys/values from it into a local queue.</p> <pre><code>public class MyRecordReader extends RecordReader&lt;LongWritable, Text&gt; { private static final int BUFFER_SIZE = 5; private static final String DELIMITER = ":"; private Queue&lt;String&gt; valueBuffer = new LinkedList&lt;String&gt;(); private Queue&lt;Long&gt; keyBuffer = new LinkedList&lt;Long&gt;(); private LongWritable key = new LongWritable(); private Text value = new Text(); private RecordReader&lt;LongWritable, Text&gt; rr; public MyRecordReader(RecordReader&lt;LongWritable, Text&gt; rr) { this.rr = rr; } @Override public void close() throws IOException { rr.close(); } @Override public LongWritable getCurrentKey() throws IOException, InterruptedException { return key; } @Override public Text getCurrentValue() throws IOException, InterruptedException { return value; } @Override public float getProgress() throws IOException, InterruptedException { return rr.getProgress(); } @Override public void initialize(InputSplit arg0, TaskAttemptContext arg1) throws IOException, InterruptedException { rr.initialize(arg0, arg1); } @Override public boolean nextKeyValue() throws IOException, InterruptedException { if (valueBuffer.isEmpty()) { while (valueBuffer.size() &lt; BUFFER_SIZE) { if (rr.nextKeyValue()) { keyBuffer.add(rr.getCurrentKey().get()); valueBuffer.add(rr.getCurrentValue().toString()); } else { return false; } } } else { if (rr.nextKeyValue()) { keyBuffer.add(rr.getCurrentKey().get()); valueBuffer.add(rr.getCurrentValue().toString()); keyBuffer.remove(); valueBuffer.remove(); } else { return false; } } key.set(keyBuffer.peek()); value.set(getValue()); return true; } private String getValue() { StringBuilder sb = new StringBuilder(); Iterator&lt;String&gt; iter = valueBuffer.iterator(); while (iter.hasNext()) { sb.append(iter.next()); if (iter.hasNext()) sb.append(DELIMITER); } return sb.toString(); } } </code></pre> <p>Then for example, you can have a custom InputFormat that extends TextInputFormat and overrides the <code>createRecordReader</code> method to call <code>super.createRecordReader</code> and return that result wrapped in a <code>MyRecordReader</code>, like this:</p> <pre><code>public class MyTextInputFormat extends TextInputFormat { @Override public RecordReader&lt;LongWritable, Text&gt; createRecordReader( InputSplit arg0, TaskAttemptContext arg1) { return new MyRecordReader(super.createRecordReader(arg0, arg1)); } } </code></pre>
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    1. USJoe K
    1. USJoe K
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    1. COSorry, I hadn't tested the code before running it. I edited it, try it now.
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    2. COThanks @joe K : Its working perfectly .
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      1. USsaurabh shashank
 

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