Cloudera Certified Developer for Apache Hadoop (CCDH) 認定 CCD-410 試験問題:

1. You want to populate an associative array in order to perform a map-side join. You've decided to put this information in a text file, place that file into the DistributedCache and read it in your Mapper before any records are processed.
Indentify which method in the Mapper you should use to implement code for reading the file and populating the associative array?

A) combine
B) configure
C) init
D) map

2. You need to perform statistical analysis in your MapReduce job and would like to call methods in the Apache Commons Math library, which is distributed as a 1.3 megabyte Java archive (JAR) file. Which is the best way to make this library available to your MapReducer job at runtime?

A) Package your code and the Apache Commands Math library into a zip file named JobJar.zip
B) Have your system administrator copy the JAR to all nodes in the cluster and set its location in the HADOOP_CLASSPATH environment variable before you submit your job.
C) When submitting the job on the command line, specify the -libjars option followed by the JAR file path.
D) Have your system administrator place the JAR file on a Web server accessible to all cluster nodes and then set the HTTP_JAR_URL environment variable to its location.

3. How are keys and values presented and passed to the reducers during a standard sort and shuffle phase of MapReduce?

A) Keys are presented to a reducer in random order; values for a given key are sorted in ascending order.
B) Keys are presented to reducer in sorted order; values for a given key are not sorted.
C) Keys are presented to reducer in sorted order; values for a given key are sorted in ascending order.
D) Keys are presented to a reducer in random order; values for a given key are not sorted.

4. You have written a Mapper which invokes the following five calls to the OutputColletor.collect method:
output.collect (new Text ("Apple"), new Text ("Red") ) ;
output.collect (new Text ("Banana"), new Text ("Yellow") ) ;
output.collect (new Text ("Apple"), new Text ("Yellow") ) ;
output.collect (new Text ("Cherry"), new Text ("Red") ) ;
output.collect (new Text ("Apple"), new Text ("Green") ) ;
How many times will the Reducer's reduce method be invoked?

A) 1
B) 0
C) 3
D) 6
E) 5

5. 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 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.
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 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.

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