Hortonworks HADOOP-PR000007 Value Pack (Frequently Bought Together)

When can a reduce class also serve as a combiner without affecting the output of a MapReduce program?

• A. When the signature of the reduce method matches the signature of the combine method.
• B. Never. Combiners and reducers must be implemented separately because they serve different purposes.
• C. Always. The point of a combiner is to serve as a mini-reducer directly after the map phase to increase performance.
• D. When the types of the reduce operation's input key and input value match the types of the reducer's output key and output value and when the reduce operation is both communicative and associative.
• E. Always. Code can be reused in Java since it is a polymorphic object-oriented programming language.

Which describes how a client reads a file from HDFS?

• A. The client queries the NameNode for the block location(s). The NameNode returns the block location(s)
  to the client. The client reads the data directory off the DataNode(s).
• B. The client contacts the NameNode for the block location(s). The NameNode contacts the DataNode
  that holds the requested data block. Data is transferred from the DataNode to the NameNode, and then
  from the NameNode to the client.
• C. The client queries all DataNodes in parallel. The DataNode that contains the requested data responds
  directly to the client. The client reads the data directly off the DataNode.
• D. The client contacts the NameNode for the block location(s). The NameNode then queries the
  DataNodes for block locations. The DataNodes respond to the NameNode, and the NameNode redirects
  the client to the DataNode that holds the requested data block(s). The client then reads the data directly
  off the DataNode.

Which HDFS command uploads a local file X into an existing HDFS directory Y?

• A. hadoop fs-put X Y
• B. hadoop scp X Y
• C. hadoop fs -get X Y
• D. hadoop fs -localPut X Y

Assuming the following Hive query executes successfully:

Which one of the following statements describes the result set?

• A. A bigram of the top 80 sentences that contain the substring "you are" in the lines column of the input
  data A1 table.
• B. A frequency distribution of the top 80 words that follow the subsequence "you are" in the lines column
  of the inputdata table.
• C. An 80-value ngram of sentences that contain the words "you" or "are" in the lines column of the
  inputdata table.
• D. A trigram of the top 80 sentences that contain "you are" followed by a null space in the lines column of
  the inputdata table.

Given the following Hive command:

Which one of the following statements is true?

• A. The files in the mydata folder are copied to a subfolder of /apps/hlve/warehouse
• B. The files in the mydata folder do not move from their current location In HDFS
• C. The files in the mydata folder are moved to a subfolder of /apps/hive/wa re house
• D. The files in the mydata folder are copied into Hive's underlying relational database