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. 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.
• B. 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.
• C. There is no difference in output between the two settings.
• 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.

Which one of the following Hive commands uses an HCatalog table named x?

• A. Hive commands cannot reference an HCatalog table
• B. SELECT * FROM org.apache.hcatalog.hive.HCatLoader('x');
• C. SELECT x.-FROM org.apache.hcatalog.hive.HCatLoader('x');
• D. SELECT * FROM x;

Which one of the following statements is true about a Hive-managed table?

• A. Hive dynamically defines the schema of the table based on the FROM clause of a SELECT query.
• B. Hive dynamically defines the schema of the table based on the format of the underlying data.
• C. When the table is dropped, the underlying folder in HDFS is deleted.
• D. Records can only be added to the table using the Hive INSERT command.

You are developing a MapReduce job for sales reporting. The mapper will process input keys
representing the year (IntWritable) and input values representing product indentifies (Text).
Indentify what determines the data types used by the Mapper for a given job.

• A. The data types specified in HADOOP_MAP_DATATYPES environment variable
• B. The InputFormat used by the job determines the mapper's input key and value types.
• C. The mapper-specification.xml file submitted with the job determine the mapper's input key and value
  types.
• D. The key and value types specified in the JobConf.setMapInputKeyClass and
  JobConf.setMapInputValuesClass methods

Analyze each scenario below and indentify which best describes the behavior of the default partitioner?

• A. The default partitioner computes the hash of the key and divides that valule modulo the number of
  reducers. The result determines the reducer assigned to process the key-value pair.
• B. The default partitioner computes the hash of the value and takes the mod of that value with the number
  of reducers. The result determines the reducer assigned to process the key-value pair.
• C. The default partitioner assigns key-values pairs to reduces based on an internal random number
  generator.
• D. The default partitioner implements a round-robin strategy, shuffling the key-value pairs to each reducer
  in turn. This ensures an event partition of the key space.
• E. The default partitioner computes the hash of the key. Hash values between specific ranges are
  associated with different buckets, and each bucket is assigned to a specific reducer.