Hortonworks Hadoop 2.0 Certification exam for Pig and Hive Developer : Apache-Hadoop-Developer valid dump

Determine which best describes when the reduce method is first called in a MapReduce job?

• A. Reduce methods and map methods all start at the beginning of a job, in order to provide optimal performance for map-only or reduce-only jobs.
• B. Reducers start copying intermediate key-value pairs from each Mapper as soon as it has completed. The reduce method is called only after all intermediate data has been copied and sorted.
• C. Reducers start copying intermediate key-value pairs from each Mapper as soon as it has completed. The programmer can configure in the job what percentage of the intermediate data should arrive before the reduce method begins.
• D. Reducers start copying intermediate key-value pairs from each Mapper as soon as it has completed. The reduce method is called as soon as the intermediate key-value pairs start to arrive.

Assuming default settings, which best describes the order of data provided to a reducer's reduce method:

• A. The keys given to a reducer aren't in a predictable order, but the values associated with those keys always are.
• B. Neither keys nor values are in any predictable order.
• C. Both the keys and values passed to a reducer always appear in sorted order.
• D. The keys given to a reducer are in sorted order but the values associated with each key are in no predictable order

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

You use the hadoop fs -put command to write a 300 MB file using and HDFS block size of 64 MB. Just after this command has finished writing 200 MB of this file, what would another user see when trying to access this life?

• A. They would see no content until the whole file written and closed.
• B. They would see the current state of the file, up to the last bit written by the command.
• C. They would see the current of the file through the last completed block.
• D. They would see Hadoop throw an ConcurrentFileAccessException when they try to access this file.

You want to perform analysis on a large collection of images. You want to store this data in HDFS and process it with MapReduce but you also want to give your data analysts and data scientists the ability to process the data directly from HDFS with an interpreted high-level programming language like Python. Which format should you use to store this data in HDFS?

• A. HTML
• B. XML
• C. JSON
• D. SequenceFiles
• E. Avro
• F. CSV