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What Is the Role of the Output Path in a Hadoop MapReduce Job?
Understand the role of the Output Path in Hadoop MapReduce jobs. Learn how FileOutputFormat.setOutputPath() specifies the HDFS directory for saving final results and why Hadoop validates this path to prevent data overwriting.
Question
What is the role of the Output Path in Hadoop jobs?
A. It defines the replication factor
B. It identifies the cluster hostname
C. It manages rack awareness
D. It specifies where the results of MapReduce jobs are stored in HDFS
Answer
D. It specifies where the results of MapReduce jobs are stored in HDFS
Explanation
In the Hadoop framework, the Output Path defines the target directory in the Hadoop Distributed File System (HDFS) where the final results of a MapReduce job will be saved. It is typically configured using methods like FileOutputFormat.setOutputPath() before the job starts. Hadoop strictly validates this path during job initialization; if the specified directory already exists, the job will fail and throw an error to prevent accidental overwriting of existing data. The Output Path does not control the replication factor, manage rack awareness, or identify cluster hostnames.