HDPCD Online Practice Questions and Answers

A combiner reduces:

A. The number of values across different keys in the iterator supplied to a single reduce method call.

B. The amount of intermediate data that must be transferred between the mapper and reducer.

C. The number of input files a mapper must process.

D. The number of output files a reducer must produce.

Consider the following two relations, A and B.

A Pig JOIN statement that combined relations A by its first field and B by its second field would produce what output?

A. 2 Jim Chris 2 3 Terry 3 4 Brian 4

B. 2 cherry 2 cherry 3 orange 4 peach

C. 2 cherry Jim, Chris 3 orange Terry 4 peach Brian

D. 2 cherry Jim 2 2 cherry Chris 2 3 orange Terry 3 4 peach Brian 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 a Writable object from an object pool.

C. It returns a reference to the same Writable object each time, but populated with different data.

D. It returns a reference to a Writable object. The API leaves unspecified whether this is a reused object or a new object.

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.

MapReduce v2 (MRv2/YARN) splits which major functions of the JobTracker into separate daemons?

Select two.

A. Heath states checks (heartbeats)

B. Resource management

C. Job scheduling/monitoring

D. Job coordination between the ResourceManager and NodeManager

E. Launching tasks

F. Managing file system metadata

G. MapReduce metric reporting

H. Managing tasks

Which two of the following statements are true about Pig's approach toward data? Choose 2 answers

A. Accepts only data that has a key/value pair structure

B. Accepts data whether it has metadata or not

C. Accepts only data that is defined by metadata tables stored in a database

D. Accepts tab-delimited text data only

E. Accepts any data: structured or unstructured

You wrote a map function that throws a runtime exception when it encounters a control character in input data. The input supplied to your mapper contains twelve such characters totals, spread across five file splits. The first four file splits each have two control characters and the last split has four control characters.

Indentify the number of failed task attempts you can expect when you run the job with mapred.max.map.attempts set to 4:

A. You will have forty-eight failed task attempts

B. You will have seventeen failed task attempts

C. You will have five failed task attempts

D. You will have twelve failed task attempts

E. You will have twenty failed task attempts

What does the following command do?

register andapos;/piggyban):/pig-files.jarandapos;;

A. Invokes the user-defined functions contained in the jar file

B. Assigns a name to a user-defined function or streaming command

C. Transforms Pig user-defined functions into a format that Hive can accept

D. Specifies the location of the JAR file containing the user-defined functions

You need to move a file titled "weblogs" into HDFS. When you try to copy the file, you can't. You know you have ample space on your DataNodes. Which action should you take to relieve this situation and store more files in HDFS?

A. Increase the block size on all current files in HDFS.

B. Increase the block size on your remaining files.

C. Decrease the block size on your remaining files.

D. Increase the amount of memory for the NameNode.

E. Increase the number of disks (or size) for the NameNode.

F. Decrease the block size on all current files in HDFS.

MapReduce v2 (MRv2/YARN) is designed to address which two issues?

A. Single point of failure in the NameNode.

B. Resource pressure on the JobTracker.

C. HDFS latency.

D. Ability to run frameworks other than MapReduce, such as MPI.

E. Reduce complexity of the MapReduce APIs.

F. Standardize on a single MapReduce API.

How are keys and values presented and passed to the reducers during a standard sort and shuffle phase of MapReduce?

A. Keys are presented to reducer in sorted order; values for a given key are not sorted.

B. Keys are presented to reducer in sorted order; values for a given key are sorted in ascending order.

C. Keys are presented to a reducer in random order; values for a given key are not sorted.

D. Keys are presented to a reducer in random order; values for a given key are sorted in ascending order.