Answer / Reetu Rana

In Hadoop MapReduce, a Reducer combines the output of multiple Mappers to produce the final result for each key. A Combiner, on the other hand, performs a partial reduction of the data before it is sent to the reducer nodes. It helps optimize the performance by reducing the amount of data that needs to be transferred over the network.

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

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How to set mappers and reducers for Hadoop jobs?

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Explain combiners.

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Explain what is the function of mapreduce partitioner?

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How many Reducers run for a MapReduce job in Hadoop?

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Explain the sequence of execution of all the components of MapReduce like a map, reduce, recordReader, split, combiner, partitioner, sort, shuffle.

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How to set the number of mappers to be created in MapReduce?

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Which among the two is preferable for the project- Hadoop MapReduce or Apache Spark?

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What is the core of the job in MapReduce framework?

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Write a short note on the disadvantages of mapreduce

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what daemons run on a master node and slave nodes?

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what is a Task Tracker in Hadoop?

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