What is Mapper in Hadoop?

561

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What is Reducer in Hadoop?

552

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What are the most common InputFormats in Hadoop?

593

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Explain InputSplit in Hadoop?

468

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What is the purpose of RecordReader in hadoop?

482

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What is Combiner in Hadoop?

534

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If no custom partitioner is defined in Hadoop then how is data partitioned before it is sent to the reducer?

451

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Why aggregation cannot be done in Mapper?

567

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Explain map-only job?

529

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What is KeyValueTextInputFormat in Hadoop?

534

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What happen if number of reducer is set to 0 in Hadoop?

498

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What is TextInputFormat in Hadoop?

521

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What is purpose of RecordWriter in Hadoop?

509

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What are the most common OutputFormat in Hadoop?

551

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What is LazyOutputFormat in Hadoop?

499

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