Hortonworks HADOOP-PR000007 問題集

質問 1：
Indentify which best defines a SequenceFile?
A. A SequenceFile contains a binary encoding of an arbitrary number key-value pairs. Each key must be
the same type. Each value must be the same type.
B. A SequenceFile contains a binary encoding of an arbitrary number of homogeneous Writable objects
C. A SequenceFile contains a binary encoding of an arbitrary number of heterogeneous Writable objects
D. A SequenceFile contains a binary encoding of an arbitrary number of WritableComparable objects, in
sorted order.
正解：A

質問 2：
You want to run Hadoop jobs on your development workstation for testing before you submit them to your
production cluster. Which mode of operation in Hadoop allows you to most closely simulate a production
cluster while using a single machine?
A. Run simldooop, the Apache open-source software for simulating Hadoop clusters.
B. Run all the nodes in your production cluster as virtual machines on your development workstation.
C. Run the hadoop command with the -jt local and the -fs file:///options.
D. Run the DataNode, TaskTracker, NameNode and JobTracker daemons on a single machine.
正解：D

質問 3：
You have a directory named jobdata in HDFS that contains four files: _first.txt, second.txt, .third.txt and
# data.txt. How many files will be processed by the FileInputFormat.setInputPaths () command when it's
given a path object representing this directory?
A. None, the directory cannot be named jobdata
B. One, no special characters can prefix the name of an input file
C. Three, the pound sign is an invalid character for HDFS file names
D. Two, file names with a leading period or underscore are ignored
E. Four, all files will be processed
正解：D

質問 4：
You've written a MapReduce job that will process 500 million input records and generated 500 million
key-value pairs. The data is not uniformly distributed. Your MapReduce job will create a significant
amount of intermediate data that it needs to transfer between mappers and reduces which is a potential
bottleneck. A custom implementation of which interface is most likely to reduce the amount of
intermediate data transferred across the network?
A. Partitioner
B. Combiner
C. WritableComparable
D. Writable
E. InputFormat
F. OutputFormat
正解：B

質問 5：
Which HDFS command displays the contents of the file x in the user's HDFS home directory?
A. hadoop fs -cat x
B. hadoop fs -cp x
C. hadoop fs -Is x
D. hdfs fs -get x
正解：A

質問 6：
Which process describes the lifecycle of a Mapper?
A. The JobTracker spawns a new Mapper to process all records in a single file.
B. The JobTracker calls the TaskTracker's configure () method, then its map () method and finally its close () method.
C. The TaskTracker spawns a new Mapper to process each key-value pair.
D. The TaskTracker spawns a new Mapper to process all records in a single input split.
正解：D

質問 7：
Which one of the following statements is true about a Hive-managed table?
A. Hive dynamically defines the schema of the table based on the FROM clause of a SELECT query.
B. When the table is dropped, the underlying folder in HDFS is deleted.
C. Hive dynamically defines the schema of the table based on the format of the underlying data.
D. Records can only be added to the table using the Hive INSERT command.
正解：B