Cloudera Certified Developer for Apache Hadoop (CCDH) 認定 CCD-410 試験問題:

1. Your cluster's HDFS block size in 64MB. You have directory containing 100 plain text files, each of which is 100MB in size. The InputFormat for your job is TextInputFormat. Determine how many Mappers will run?

A) 640
B) 100
C) 200
D) 64

2. 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) Two, file names with a leading period or underscore are ignored
B) Three, the pound sign is an invalid character for HDFS file names
C) One, no special characters can prefix the name of an input file
D) Four, all files will be processed
E) None, the directory cannot be named jobdata

3. A combiner reduces:

A) The number of input files a mapper must process.
B) The number of output files a reducer must produce.
C) The number of values across different keys in the iterator supplied to a single reduce method call.
D) The amount of intermediate data that must be transferred between the mapper and reducer.

4. In the reducer, the MapReduce API provides you with an iterator over Writable values. What does calling the next () method return?

A) It returns a reference to a different Writable object time.
B) It returns a reference to the same Writable object each time, but populated with different data.
C) It returns a reference to a Writable object. The API leaves unspecified whether this is a reused object or a new object.
D) It returns a reference to a Writable object from an object pool.
E) It returns a reference to the same Writable object if the next value is the same as the previous value, or a new Writable object otherwise.

5. 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 DataNode, TaskTracker, NameNode and JobTracker daemons on a single machine.
D) Run the hadoop command with the -jt local and the -fs file:///options.

質問と回答：