DATABASE FUNDAMENTALS
BASICS OF BIG DATA
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Map-Side join
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Reduce-Side join
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Either A or B
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None of the above
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Detailed explanation-1: -As discussed earlier, the reduce side join is a process where the join operation is performed in the reducer phase. Basically, the reduce side join takes place in the following manner: Mapper reads the input data which are to be combined based on common column or join key.
Detailed explanation-2: -Hence without using a Map/Reduce step, a join could be performed within a mapper. As a conclusion, On compare to reduce side, Map side join is efficient but it requires the strict format.
Detailed explanation-3: -In Map-side join, all the task to join the records will be done by the mapper. This type of join is suitable for small sized tables. In Reduce-side join, the join task will be done by the reducer.
Detailed explanation-4: -Disadvantages of Map-side join: Map side join is adequate only when one of the tables on which you perform map-side join operation is small enough to fit into the memory. Hence it is not suitable to perform map-side join on the tables which are huge data in both of them.
Detailed explanation-5: -Join operations in Hadoop MapReduce can be classified into two types. They are Map-side Join and Reduce-side Join.