MapReduce Interview Questions, Answers for Freshers and Experienced asked in various Company Job Interviews

MapReduce Interview Questions

Questions Answers Views Company eMail

What are combiners? When should I use a combiner in my MapReduce Job?

899

In Map Reduce why map write output to Local Disk instead of HDFS?

902

What is a partitioner and how the user can control which key will go to which reducer?

938

How does Mappers run method works?

891

How does MapReduce framework view its input internally?

867

What are the steps involved in MapReduce framework?

979

What is the Job interface in MapReduce framework?

906

How to overwrite an existing output file during execution of mapreduce jobs?

MRO,

1091

Detail description of the Reducer phases?

851

Can there be no Reducer?

839

What is the utility of using Writable Comparable Custom Class in Map Reduce code?

988

What is the core of the job in MapReduce framework?

848

MapReduce Types and Formats and Setting up a Hadoop Cluster?

904

It can be possible that a Job has 0 reducers?

964

Why Mapreduce output written in local disk?

998

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Un-Answered Questions { MapReduce }

What are the the issues associated with the map and reduce slots based mechanism in mapReduce?

644

Explain what is distributed cache in mapreduce framework?

615

Illustrate a simple example of the working of MapReduce.

629

What happens when a DataNode fails during the write process?

638

Can you tell us how many daemon processes run on a hadoop system?

593

What is the default value of map and reduce max attempts?

931

what is "map" and what is "reducer" in Hadoop?

632

What is heartbeat in hdfs? Explain.

681

What is reduce side join in mapreduce?

613

Explain task granularity

647

Define Writable data types in Hadoop MapReduce?

638

what is a sequence file in Hadoop?

676

Explain the input type/format in mapreduce by default?

579

How to set the number of mappers for a MapReduce job?

686

What is the sequence of execution of map, reduce, recordreader, split, combiner, partitioner?

699

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