Free Cloudera CCD-333 Exam Dumps Questions & Answers

You write a MapReduce job to process 100 files in HDFS. Your MapReduce algorithm uses TextInputFormat and the IdentityReducer: the mapper applies a regular expression over input values and emits key-value pairs with the key consisting of the matching text, and the value containing the filename and byte offset. Determine the difference between setting the number of reducers to zero.

• A.  There is no difference in output between the two settings.
• B.  With zero reducers, instances of matching patterns are stored in multiple files on HDFS. With one reducer, all instances of matching patterns are gathered together in one file on HDFS.
• C.  With zero reducers, all instances of matching patterns are gathered together in one file on HDFS. With one reducer, instances of matching patterns stored in multiple files on HDFS.
• D.  With zero reducers, no reducer runs and the job throws an exception. With one reducer, instances of matching patterns are stored in a single file on HDFS.

You have written a Mapper which invokes the following five calls to the outputcollector.collect method:

How many times will the Reducer's reduce method be invoked.

• A.  1
• B.  3
• C.  6
• D.  0
• E.  5

The Hadoop framework provides a mechanism for coping with machine issues such as faulty configuration or impending hardware failure. MapReduce detects that one or a number of machines are performing poorly and starts more copies of a map or reduce task. All the tasks run simultaneously and the task that finish first are used. This is called:

• A.  Default Partitioner
• B.  Combiner
• C.  Speculative Execution
• D.  IdentityMapper
• E.  IdentityReducer

Which statement best describes the data path of intermediate key-value pairs (i.e., output of the mappers)?

• A.  Intermediate key-value pairs are written to HDFS. Reducers copy the intermediate data to the local disks of the machines running the reduce tasks.
• B.  Intermediate key-value pairs are written to HDFS. Reducers read the intermediate data from HDFS.
• C.  Intermediate key-value pairs are written to the local disks of the machines running the map tasks, and are then copied to HDFS. Reducers read the intermediate data from HDFS.
• D.  Intermediate key-value pairs are written to the local disks of the machines running the map tasks, and then copied to the machine running the reduce tasks.

What happens in a MapReduce job when you set the number of reducers to zero?

• A.  Setting the number of reducers to zero is invalid, and an exception is thrown.
• B.  No reducer executes, but the mappers generate no output.
• C.  No reducer executes, but the outputs of all the mappers are gathered together and written to a single file in HDFS.
• D.  No reducer executes, and the output of each mapper is written to a separate file in HDFS.