What is Mapper in Hadoop?

503

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What is Reducer in Hadoop?

506

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What are the most common InputFormats in Hadoop?

550

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Explain InputSplit in Hadoop?

434

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What is the purpose of RecordReader in hadoop?

442

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What is Combiner in Hadoop?

495

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

421

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Why aggregation cannot be done in Mapper?

520

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Explain map-only job?

489

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What is KeyValueTextInputFormat in Hadoop?

482

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

465

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What is TextInputFormat in Hadoop?

473

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What is purpose of RecordWriter in Hadoop?

477

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What are the most common OutputFormat in Hadoop?

518

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What is LazyOutputFormat in Hadoop?

460

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