APACHE-HADOOP-DEVELOPER Online Practice Questions and Answers

You need to move a file titled "weblogs" into HDFS. When you try to copy the file, you can't. You know you have ample space on your DataNodes. Which action should you take to relieve this situation and store more files in HDFS?

A. Increase the block size on all current files in HDFS.

B. Increase the block size on your remaining files.

C. Decrease the block size on your remaining files.

D. Increase the amount of memory for the NameNode.

E. Increase the number of disks (or size) for the NameNode.

F. Decrease the block size on all current files in HDFS.

You want to understand more about how users browse your public website, such as which pages they visit prior to placing an order. You have a farm of 200 web servers hosting your website. How will you gather this data for your analysis?

A. Ingest the server web logs into HDFS using Flume.

B. Write a MapReduce job, with the web servers for mappers, and the Hadoop cluster nodes for reduces.

C. Import all users' clicks from your OLTP databases into Hadoop, using Sqoop.

D. Channel these clickstreams inot Hadoop using Hadoop Streaming.

E. Sample the weblogs from the web servers, copying them into Hadoop using curl.

Which HDFS command displays the contents of the file x in the user's HDFS home directory?

A. hadoop fs -Is x

B. hdfs fs -get x

C. hadoop fs -cat x

D. hadoop fs -cp x

Which Hadoop component is responsible for managing the distributed file system metadata?

A. NameNode

B. Metanode

C. DataNode

D. NameSpaceManager

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 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.

C. 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.

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.

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 Hadoop throw an ConcurrentFileAccessException when they try to access this file.

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 no content until the whole file written and closed.

What is a SequenceFile?

A. A SequenceFile contains a binary encoding of an arbitrary number of homogeneous writable objects.

B. A SequenceFile contains a binary encoding of an arbitrary number of heterogeneous writable objects.

C. A SequenceFile contains a binary encoding of an arbitrary number of WritableComparable objects, in sorted order.

D. A SequenceFile contains a binary encoding of an arbitrary number key-value pairs. Each key must be the same type. Each value must be same type.

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. An 80-value ngram of sentences that contain the words "you" or "are" in the lines column of the inputdata table.

C. A trigram of the top 80 sentences that contain "you are" followed by a null space in the lines column of the inputdata table.

D. A frequency distribution of the top 80 words that follow the subsequence "you are" in the lines column of the inputdata table.

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. 6

B. 3

C. 1

D. 0

E. 5

Consider the following two relations, A and B.

A Pig JOIN statement that combined relations A by its first field and B by its second field would produce what output?

A. 2 Jim Chris 2 3 Terry 3 4 Brian 4

B. 2 cherry 2 cherry 3 orange 4 peach

C. 2 cherry Jim, Chris 3 orange Terry

4 peach Brian

D. 2 cherry Jim 2 2 cherry Chris 2 3 orange Terry 3 4 peach Brian 4