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From Doug Cutting <cutt...@apache.org>
Subject Re: reading zip files
Date Thu, 11 May 2006 18:50:54 GMT
Vijay Murthi wrote:
> I have just started looking at Hadoop source code. How can I use each
> file a distinct split? Already my data is evenly distributed across
> these compressed files.  

Implement your own InputFormat.


In particular, your getSplits implementation should return a single 
split per input file, ignoring the numSplits parameter.

You can probably subclass InputFormatBase, and have your getSplits 
method simply call listPaths() and then construct and return a single 
split per path returned.

Your RecordReader implementation might then look something like:

   public RecordReader getRecordReader(FileSystem fs, FileSplit split,
                                       JobConf job, Reporter reporter)
     throws IOException {

     final BufferedReader in =
       new BufferedReader(new InputStreamReader
         (new GZIPInputStream(fs.open(split.getPath()))));

     return new RecordReader() {
         long position;

         public synchronized boolean next(Writable key, Writable value)
           throws IOException {
           String line = in.readLine();
           if (line != null) {
             position += line.length();
             return true;
           return false;

         public synchronized long getPos() throws IOException {
           return position;

         public synchronized void close() throws IOException {


Then include your InputFormat's class file in your job's jar file.


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