Answer / Jwala Singh

Combiners in MapReduce are a technique used to optimize the sorting phase. They allow intermediate key-value pairs to be aggregated on each mapper node before sending them to the reducer nodes for final aggregation. This reduces the amount of data that needs to be shuffled between mappers and reducers, thereby improving the overall performance and reducing network traffic.

What is the next step after Mapper or MapTask?

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how indexing in HDFS is done?

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

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What is the best way to copy files between HDFS clusters?

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What is difference between a MapReduce InputSplit and HDFS block

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How to create custom key and custom value in MapReduce Job?

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How can we control particular key should go in a specific reducer?

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MapReduce Types and Formats and Setting up a Hadoop Cluster?

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Is it possible to split 100 lines of input as a single split in MapReduce?

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What main configuration parameters are specified in mapreduce?

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What is a IdentityMapper and IdentityReducer in MapReduce ?

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Explain task granularity

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