Hortonworks HDPCD 問題集

質問 1：
Which Two of the following statements are true about hdfs? Choose 2 answers
A. Block sizes for all files must be the same size
B. HDFS works best when storing a large number of relatively small files
C. An HDFS file that is larger than dfs.block.size is split into blocks
D. Blocks are replicated to multiple datanodes
正解：C,D

質問 2：
Table metadata in Hive is:
A. Stored as metadata on the NameNode.
B. Stored in ZooKeeper.
C. Stored in the Metastore.
D. Stored along with the data in HDFS.
正解：C
解説: (Topexam メンバーにのみ表示されます)

質問 3：
Examine the following Pig commands:

Which one of the following statements is true?
A. The reducers will only output the first 20% of the data passed from the mappers
B. A random sample of approximately 20% of the data will be output
C. The SAMPLE command generates an "unexpected symbol" error
D. Each MapReduce task will terminate after executing for 0.2 minutes
正解：B

質問 4：
Which two of the following are true about this trivial Pig program' (choose Two)

A. The contents of myfile appear on stdout
B. Pig assumes the contents of myfile are comma delimited
C. ABC has a schema associated with it
D. myfile is read from the user's home directory in HDFS
正解：A,D

質問 5：
You write MapReduce job to process 100 files in HDFS. Your MapReduce algorithm uses
TextInputFormat: the mapper applies a regular expression over input values and emits key-values 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 reduces to one and settings the number of reducers to zero.
A. With zero reducers, all instances of matching patterns are gathered together in one file on HDFS. With one reducer, instances of matching patterns are stored in multiple files on HDFS.
B. There is no difference in output between the two settings.
C. 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.
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.
正解：C
解説: (Topexam メンバーにのみ表示されます)

質問 6：
Given the following Hive command:
INSERT OVERWRITE TABLE mytable SELECT * FROM myothertable;
Which one of the following statements is true?
A. The statement is not a valid Hive command
B. Any existing data in mytable will be overwritten
C. A new table named mytable is created, and the contents of myothertable are copied into mytable
D. The contents of myothertable are appended to mytable
正解：B

質問 7：
What does the following WebHDFS command do?
Curl -1 -L "http://host:port/webhdfs/v1/foo/bar?op=OPEN"
A. List a directory /foo
B. Read a file /foo/bar
C. Make a directory /foo/bar
D. Delete a directory /foo/bar
正解：B

質問 8：
You have the following key-value pairs as output from your Map task: (the, 1)
(fox, 1)
(faster, 1)
(than, 1)
(the, 1)
(dog, 1)
How many keys will be passed to the Reducer's reduce method?
A. One
B. Three
C. Six
D. Five
E. Two
F. Four
正解：D
解説: (Topexam メンバーにのみ表示されます)