title: How to have lzo compression in hadoop mapreduce?
body: <p>I want to use lzo to compress map output but I can't run it! The version of Hadoop I used is <code>0.20.2</code>. I set:</p>
  
  <pre><code>conf.set("mapred.compress.map.output", "true") 
  conf.set("mapred.map.output.compression.codec",
  "org.apache.hadoop.io.compress.LzoCodec");
  </code></pre>
  
  <p>When I run the jar file in Hadoop it shows an exception that can't write map output.</p>
  
  <p>Do I have to install lzo? 
  What do I have to do to use lzo?</p>