[Hadoop Wiki] Update of "CompressedStorage" by Evan

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The following page has been changed by Evan:
http://wiki.apache.org/hadoop/CompressedStorage

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  SET hive.exec.compress.output=TRUE; 
  SET io.seqfile.compression.type=BLOCK; -- NONE/RECORD/BLOCK (see below)
  INSERT OVERWRITE TABLE raw_sequnce SELECT LINE FROM raw;
+ 
+ INSERT OVERWRITE TABLE raw_sequnce SELECT * FROM raw; -- The previous line did not work for me, but this does.
  }}}
  
  The value for io.seqfile.compression.type determines how the compression is performed. If you set it to RECORD you will get as many output files as the number of map/reduce jobs. If you set it to BLOCK, you will get as many output files as there were input files. There is a tradeoff involved here -- large number of output files => more parellel map jobs => lower compression ratio.