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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…

Python Advanced For Loop With Example

Basically, For Loop reads input value and stores in a variable. So For Loop in Python needs two arguments. The two arguments are VARIABLE and IN. So far so good. The next part of the article and examples well explained how it works and how to get the index for each input supplied.

for loops in python

In Python, for loop list and count are related to the same logic. In the below example, I have taken one array and I counted using for loop, the number of elements in the input list.

For loop Syntax

for count in[1, 2, 3]: 
print(count)
print(’Yes’*count)

The first step, How the above syntax works are what I want to share with you. The 'in' represents input array for Python for loop. That means the for loop works 3 times in Python. It displays only 3 times. The third step is just to give 'yes', which will multiply with 'count' for 3 times.

This is the whole story of for loop in Python. In the second step, print just displays values of input that stored in the for loop variable of 'count'.

The 'count' gets values one by one from for loop input array. When you used the Shell to enter a loop, there was a reason that the interpreter waited to respond until after you entered an empty line: The interpreter did not know how long the loop block was going to be! The empty line is a signal to the interpreter that you are done with the loop block.

The index in For loop 

A small example is given to get index and value from for loop.
#Get index using for loop
#You will get index and value
mylist=[1, 2, 3]: 
for idx, val in enumerate(mylist):
    print(idx, val)

Video Tutorial

I have created a small video so that you can play quickly and check how for loop works in Python.
Also, read

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