Apache-Hadoop-Developer最も有効な質問と解答で勉強

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. No, because the Combiner is incompatible with a mapper which doesn't use the same data type for both the key and value.
• B. Yes, because Java is a polymorphic object-oriented language and thus reducer code can be reused as a combiner.
• C. Yes, because the sum operation is both associative and commutative and the input and output types to the reduce method match.
• D. No, because the sum operation in the reducer is incompatible with the operation of a Combiner.
• E. No, because the Reducer and Combiner are separate interfaces.

For each intermediate key, each reducer task can emit:

• A. One final key-value pair per value associated with the key; no restrictions on the type.
• B. As many final key-value pairs as desired, as long as all the keys have the same type and all the values have the same type.
• C. As many final key-value pairs as desired. There are no restrictions on the types of those key-value pairs (i.e., they can be heterogeneous).
• D. As many final key-value pairs as desired, but they must have the same type as the intermediate key-value pairs.
• E. One final key-value pair per key; no restrictions on the type.

What are the TWO main components of the YARN ResourceManager process? Choose 2 answers

• A. Job Tracker
• B. Scheduler
• C. Applications Manager
• D. Task Tracker

Which project gives you a distributed, Scalable, data store that allows you random, realtime read/write access to hundreds of terabytes of data?

• A. Flume
• B. Oozie
• C. Sqoop
• D. Hue
• E. Hive
• F. Pig
• G. HBase

On a cluster running MapReduce v1 (MRv1), a TaskTracker heartbeats into the JobTracker on your cluster, and alerts the JobTracker it has an open map task slot.
What determines how the JobTracker assigns each map task to a TaskTracker?

• A. The amount of RAM installed on the TaskTracker node.
• B. The amount of free disk space on the TaskTracker node.
• C. The average system load on the TaskTracker node over the past fifteen (15) minutes.
• D. The location of the InsputSplit to be processed in relation to the location of the node.
• E. The number and speed of CPU cores on the TaskTracker node.