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The Ultimate Cheat Sheet On Hadoop

Top 20 frequently asked questions to test your Hadoop knowledge given in the below Hadoop cheat sheet. Try finding your own answers and match the answers given here.




Question #1 

You have written a MapReduce job that will process 500 million input records and generate 500 million key-value pairs. The data is not uniformly distributed. Your MapReduce job will create a significant amount of intermediate data that it needs to transfer between mappers and reducers which is a potential bottleneck. A custom implementation of which of the following interfaces is most likely to reduce the amount of intermediate data transferred across the network?



A. Writable
B. WritableComparable
C. InputFormat
D. OutputFormat
E. Combiner
F. Partitioner
Ans: e




Question #2 

Where is Hive metastore stored by default ?


A. In HDFS
B. In client machine in the form of a flat file.
C. In client machine in a derby database
D. In lib directory of HADOOP_HOME, and requires HADOOP_CLASSPATH to be modified.
Ans: c




Question…

Big Data: Top Hadoop Interview Questions (4 of 5)

Hadoop,Jobs,Career
1) What is MAP Reduce program?
- You need to give actual steps in this program
- You have to write scripts and codes

2) What is MAPReduce?
-Mapreduce is a data processing model
-It is combination of 2 parts. One is Mappers and the other one is Reducers

3)What will happen in Mapping phase?
It takes the input data, and feeds each data element into the mapper

4)What is the function of Reducer?
The reducer process all outputs from mapper and arrives at a final result

5)What kind of input required for Mapreduce?
It should be structured in the form of (Key,Value) pairs

6)What is HDFS?
HDFS is a file system designed for large-scale data processing under frameworks such as MapReduce.

7) Is HDFS like UNIX?
No, but commands in HDFS works similarly to UNIX

8) What is Simple file command?
hadoop fs -ls

9) How to copy data into HDFS file system?

Copy a file into HDFS from local system

10) What is default working directory in HDFS?
/user/$USER
$USER ==> Your login user name

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