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    <p>If you want Hadoop to process a 100 GiB apache logfile "line by line" you are essentially doing the same as what you want: A large body of text split into pieces.</p> <p>The normal way for doing that in Hadoop (as you tagged the question with this) is using the <a href="http://svn.apache.org/viewvc/hadoop/mapreduce/trunk/src/java/org/apache/hadoop/mapreduce/lib/input/TextInputFormat.java?view=markup" rel="nofollow">TextInputFormat</a> which uses <a href="http://svn.apache.org/viewvc/hadoop/mapreduce/trunk/src/java/org/apache/hadoop/mapreduce/lib/input/LineRecordReader.java?view=markup" rel="nofollow">LineRecordReader</a> which uses <a href="http://svn.apache.org/viewvc/hadoop/common/trunk/src/java/org/apache/hadoop/util/LineReader.java?view=markup" rel="nofollow">LineReader</a> to split the Text file on the "end-of-line" separator. What you want is essentially the same with one difference: split on something different.</p> <p>Sorting the resulting values (in Hadoop) is essentially done by employing what is called "Secondary Sort" (<a href="http://svn.apache.org/viewvc/hadoop/mapreduce/trunk/src/examples/org/apache/hadoop/examples/SecondarySort.java?view=markup" rel="nofollow">See the Hadoop example</a> and <a href="http://books.google.nl/books?id=bKPEwR-Pt6EC&amp;pg=PA227&amp;lpg=PA227&amp;dq=hadoop+definitive+guide+secondary+sort&amp;source=bl&amp;hl=en#v=onepage&amp;q&amp;f=false" rel="nofollow">the explanation in Tom's book</a>).</p> <p>So what I would recommend doing is</p> <ol> <li>Make your own variation on <a href="http://svn.apache.org/viewvc/hadoop/mapreduce/trunk/src/java/org/apache/hadoop/mapreduce/lib/input/TextInputFormat.java?view=markup" rel="nofollow">TextInputFormat</a>/<a href="http://svn.apache.org/viewvc/hadoop/mapreduce/trunk/src/java/org/apache/hadoop/mapreduce/lib/input/LineRecordReader.java?view=markup" rel="nofollow">LineRecordReader</a>/<a href="http://svn.apache.org/viewvc/hadoop/common/trunk/src/java/org/apache/hadoop/util/LineReader.java?view=markup" rel="nofollow">LineReader</a> that reads and extracts the individual parts of your String based on you separator. </li> <li>Create a map that rewrites the information to do Secondary Sort.</li> <li>Create the correct partition, group and key comparator classes/methods to do the sorting.</li> <li>Create a reduce where you receive the sorted information which you can the process further.</li> </ol> <p>HTH</p>
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