MapReduce Interview Questions
Questions Answers Views Company eMail

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

637

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

637

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

624

How does Mappers run method works?

594

How does MapReduce framework view its input internally?

580

What are the steps involved in MapReduce framework?

601

What is the Job interface in MapReduce framework?

629

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

MRO,

831

Detail description of the Reducer phases?

572

Can there be no Reducer?

566

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

594

What is the core of the job in MapReduce framework?

570

MapReduce Types and Formats and Setting up a Hadoop Cluster?

580

It can be possible that a Job has 0 reducers?

621

Why Mapreduce output written in local disk?

603


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Un-Answered Questions { MapReduce }

What is the key- value pair in Hadoop MapReduce?

394


what are the main configuration parameters that user need to specify to run Mapreduce Job ?

357


What is difference between an input split and hdfs block?

342


Which interface needs to be implemented to create Mapper and Reducer for the Hadoop?

857


Detail description of the Reducer phases?

572






How does Hadoop Classpath plays a vital role in stopping or starting in Hadoop daemons?

453


Why MapReduce uses the key-value pair to process the data?

342


Explain how mapreduce works.

353


how Hadoop is different from other data processing tools?

368


How hadoop mapreduce works?

359


What is the inputsplit in map reduce software?

366


Is it mandatory to set input and output type/format in MapReduce?

426


What is Distributed Cache in the MapReduce Framework?

352


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

353


How to get the single file as the output from MapReduce Job?

357