Hortonworks Apache-Hadoop-Developer 問題集

質問 1：
You want to count the number of occurrences for each unique word in the supplied input data. You've decided to implement this by having your mapper tokenize each word and emit a literal value 1, and then have your reducer increment a counter for each literal 1 it
receives. After successful implementing this, it occurs to you that you could optimize this by specifying a combiner. Will you be able to reuse your existing Reduces as your combiner in this case and why or why not?
A. Yes, because Java is a polymorphic object-oriented language and thus reducer code can be reused as a combiner.
B. No, because the Combiner is incompatible with a mapper which doesn't use the same data type for both the key and value.
C. No, because the Reducer and Combiner are separate interfaces.
D. Yes, because the sum operation is both associative and commutative and the input and output types to the reduce method match.
E. No, because the sum operation in the reducer is incompatible with the operation of a Combiner.
正解：D
解説: (Topexam メンバーにのみ表示されます)

質問 2：
Given the following Pig command:
logevents = LOAD 'input/my.log' AS (date:chararray, levehstring, code:int, message:string);
Which one of the following statements is true?
A. The logevents relation represents the data from the my.log file, using a tab as the parsing delimiter
B. The statement is not a valid Pig command
C. The first field of logevents must be a properly-formatted date string or table return an error
D. The logevents relation represents the data from the my.log file, using a comma as the parsing delimiter
正解：A

質問 3：
In Hadoop 2.0, which TWO of the following processes work together to provide automatic failover of the NameNode? Choose 2 answers
A. JournalNode
B. ZooKeeper
C. ZKFailoverController
D. QuorumManager
正解：A,C

質問 4：
Given the following Pig commands:

Which one of the following statements is true?
A. The $1 variable represents the second column of data in 'my.log'
B. The grouped relation is not valid
C. The severe relation is not valid
D. The $1 variable represents the first column of data in 'my.log'
正解：A

質問 5：
In a MapReduce job, the reducer receives all values associated with same key. Which statement best describes the ordering of these values?
A. The values are arbitrarily ordered, and the ordering may vary from run to run of the same MapReduce job.
B. The values are arbitrary ordered, but multiple runs of the same MapReduce job will always have the same ordering.
C. Since the values come from mapper outputs, the reducers will receive contiguous sections of sorted values.
D. The values are in sorted order.
正解：A
解説: (Topexam メンバーにのみ表示されます)

質問 6：
When is the earliest point at which the reduce method of a given Reducer can be called?
A. As soon as at least one mapper has finished processing its input split.
B. It depends on the InputFormat used for the job.
C. As soon as a mapper has emitted at least one record.
D. Not until all mappers have finished processing all records.
正解：D
解説: (Topexam メンバーにのみ表示されます)

質問 7：
Which one of the following statements regarding the components of YARN is FALSE?
A. A client application submits a YARW job to the ResourceManager
B. The ResourceManager is responsible for scheduling and allocating resources
C. The ResourceManager monitors and restarts any failed Containers
D. A Container executes a specific task as assigned by the ApplicationMaster
正解：C