DATABASE FUNDAMENTALS
BASICS OF BIG DATA
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Consider the pseudo-code for MapReduce’s WordCount example (not shown here). Let’s now assume that you want to determine the frequency of phrases consisting of 3 words each instead of determining the frequency of single words. Which part of the pseudo-code do you need to adapt?
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Only map()
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Only reduce()
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Both map() and reduce()
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The code does not have to be changed
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Explanation:
Detailed explanation-1: -Incorrect. Heartbeat messages are not send by DataNodes, they are only sent by the NameNode, one every 5 seconds.
Detailed explanation-2: -A map() function can emit up to a maximum number of key/value pairs (depending on the Hadoop environment). A map() function can emit anything between zero and an unlimited number of key/value pairs. A reduce() function can iterate over key/value pairs multiple times.
Detailed explanation-3: -Q 26-Which one of the following statements is true regarding <key, value> pairs of a MapReduce job? A-A key class must implement Writable.
There is 1 question to complete.