Bigdata - Interview Questions and Answers for 'Barclays' | Search Interview Question

Bigdata - Interview Questions and Answers for 'Barclays' - 2 question(s) found - Order By Newest

Q1. What is the difference between namenode and datanode in Hadoop?

Ans. NameNode stores MetaData (No of Blocks, On Which Rack which DataNode is stored etc) whereas the DataNode stores the actual Data.

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Q2. What is the use of Combiners ?

BigData

Ans. Combiners are used to increase the efficiency of a Map Reduce program. They are used to aggregate intermediate map output locally on individual mapper outputs. Combiners can help you reduce the amount of data that needs to be transferred across to the reducers.