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: -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-2: -Map join is a type of join where a smaller table is loaded in memory and the join is done in the map phase of the MapReduce job. As no reducers are necessary, map joins are way faster than the regular joins. In Qubole Hive, the mapjoin options are enabled by default/have default values.
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: -Map-side join – When the join is performed by the mapper, it is called as map-side join. In this type, the join is performed before data is actually consumed by the map function. It is mandatory that the input to each map is in the form of a partition and is in sorted order.