All keys used for intermediate output from mappers must:

On a cluster running MapReduce v1 (MRv1), a TaskTracker heartbeats into the JobTracker on
your cluster, and alerts the JobTracker it has an open map task slot.
What determines how the JobTracker assigns each map task to a TaskTracker?

What is a SequenceFile?

A client application creates an HDFS file named foo.txt with a replication factor of 3. Identify which
best describes the file access rules in HDFS if the file has a single block that is stored on data
nodes A, B and C?

In a MapReduce job, you want each of your input files processed by a single map task. How do
you configure a MapReduce job so that a single map task processes each input file regardless of
how many blocks the input file occupies?

Which process describes the lifecycle of a Mapper?

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

To process input key-value pairs, your mapper needs to lead a 512 MB data file in memory. What
is the best way to accomplish this?

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?

In a MapReduce job, the reducer receives all values associated with same key. Which statement
best describes the ordering of these values?