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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…

RDBMS Vs NOSQL awesome differences to read now

NoSQL and RDBMS or SQL are different from each other. You may ask what is the difference. Below explained in a way that you can understand quickly.

rdbms vs no sql

Traditional Database

  • A schema is required. All traditional data warehouses using RDBMS to store datamarts.
  • Databases understand SQL language. It has a specific format and rules to interact with traditional databases.
  • Less scalable. It has certain limitations. 
  • Expensive to make the databases as scalable
  • Data should be in a certain format.
  • Data stored in row format.

NoSQL database

The growing internet usage and involving of a number of devices caused to invent databases that have the capability to store any kind of data.

More: MongoDB 3.2 fundamentals for Developers-Learn with Exercises

NoSQL Special Features

  • The schema is not required. Ability to handle multiple data types. This is the power of NoSQL.
  • NoSQL is much suitable for analytical databases. Since those should be flexible, Scalable and ability to store any formatted data.
  • The increased usage of web applications, the availability of broadband for the common man, caused the generating of a variety of data. So NoSQL is absolutely needed for the new generation businesses.
  • Data stored in column format. In the form of key value pairs.
  • Python, Ruby, PHP, and Java are top languages you need to interact with NoSQL databases.

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