title: Why can't hadoop split up a large text file and then compress the splits using gzip?
body: <p>I've recently been looking into hadoop and HDFS. When you load a file into HDFS, it will normally split the file into 64MB chunks and distribute these chunks around your cluster. Except it can't do this with gzip'd files because a gzip'd file can't be split. I <strong>completely</strong> understand why this is the case (I don't need anyone explaining why a gzip'd file can't be split up). But why couldn't HDFS take a plain text file as input and split it like normal, then compress each split using gzip separately? When any split is accessed, it's just decompressed on the fly.</p>
  
  <p>In my scenario, each split is compressed completely independently. There's no dependencies between splits, so you don't need the entire original file to decompress any one of the splits. That is the approach this patch takes: <a href="https://issues.apache.org/jira/browse/HADOOP-7076" rel="noreferrer">https://issues.apache.org/jira/browse/HADOOP-7076</a>, note that this is <strong>not</strong> what I'd want.</p>
  
  <p>This seems pretty basic... what am I missing? Why couldn't this be done? Or if it could be done, why have the hadoop developers not looked down this route? It seems strange given how much discussion I've found regarding people wanting split gzip'd files in HDFS.</p>