What is the role of the setMapOutputCompressorClass class in the development of MapReduce applications?

Question

Options

• ASet the compression method of Smap input
• BSet the delivery method of map output
• CSet the compression method of map output
• DSet the compression method of reduce output

• A
  6% (3)
• B
  4% (2)
• C
  80% (43)
• D
  11% (6)

Explanation

setMapOutputCompressorClass is a method in Hadoop's JobConf/Job API that specifies which compression codec to apply to the output of the Map phase before it is shuffled and sorted to reducers - making C correct. Option A is wrong because map input compression is configured separately via setInputFormat or codec settings on the input data itself, not this method. Option B is wrong because "delivery method" implies the shuffle/transfer mechanism, which is handled by partitioners and the shuffle framework, not a compressor class. Option D is wrong because reduce output compression is controlled by a distinct method: setOutputCompressorClass (or FileOutputFormat.setCompressOutput).

Memory tip: Parse the name literally - Map (map phase) + Output (after mapping, before reduce) + Compressor (compression) + Class (the codec class to use). Each word maps directly to what it configures.

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