Hortonworks HADOOP-PR000007 Exam Questions & Answers

Which HDFS command copies an HDFS file named foo to the local filesystem as localFoo?

A. hadoop fs -get foo LocalFoo

B. hadoop -cp foo LocalFoo

C. hadoop fs -Is foo

D. hadoop fs -put foo LocalFoo

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. There is no difference in output between the two settings.

B. 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.

C. 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.

D. 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.

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