MapReduce Framework and Its Implementation in Hadoop DATA-SCIENCE-OPTIMIZE Practice Questions (Page 2)

Questions 6–10

1. 6foundation · easy

   Which strategy is commonly used to reduce the amount of data transferred during the shuffle phase in a Hadoop MapReduce job?

   • AEnabling compression of intermediate map outputs.
   • BUsing a larger block size for HDFS.
   • CIncreasing the number of mappers.
   • DSetting the number of reducers to one.
   Reveal Solution Discussion Select an answer first
2. 7foundation · easy

   In the classic Hadoop MapReduce implementation (before YARN), what was the role of the JobTracker?

   • AIt stored the input and output data for the job.
   • BIt coordinated job execution by scheduling tasks and tracking their progress.
   • CIt ran the map and reduce tasks on each slave node.
   • DIt compiled the MapReduce program into executable code.
   Reveal Solution Discussion Select an answer first
4. 8foundation · easy

   Which output format in Hadoop MapReduce is designed to write binary key-value pairs in a compact, splittable format?

   • AMultipleOutputs
   • BSequenceFileOutputFormat
   • CNullOutputFormat
   • DTextOutputFormat
   Reveal Solution Discussion Select an answer first
5. 9foundation · easy

   What is the primary purpose of the shuffle phase in the MapReduce paradigm?

   • ATo compress the intermediate data to reduce storage usage.
   • BTo sort the intermediate keys and transfer the data from map outputs to the appropriate reducers.
   • CTo combine the output of multiple reducers into a single final result.
   • DTo replicate the input data across multiple nodes for fault tolerance.
   Reveal Solution Discussion Select an answer first
6. 10application · medium

   A MapReduce job calculates the average rating for each product from a large dataset of user ratings. The job currently runs with a combiner that computes the sum and count for each product. The reduce phase then computes the average. The job is slow due to the large amount of intermediate data. Which optimization is most effective?

   • AReplace the combiner with a custom combiner that computes the average directly.
   • BKeep the combiner but ensure it emits (product, sum) and (product, count) pairs.
   • CIncrease the number of reducers to reduce the data per reducer.
   • DRemove the combiner to simplify the job.
   Reveal Solution Discussion Select an answer first