H13-723_V2.0 · Question #71
In a MapReduce application, the output of the map function is processed by the MapReduce framework and sent to the reduce function. This process is based on key-value pairs for sorting and grouping.
The correct answer is A. True. Option A is correct because MapReduce's core mechanism relies entirely on key-value pairs: the map function emits intermediate key-value pairs, the framework then sorts and groups all values by key (the "shuffle and sort" phase), and finally sends each unique key with its…
Question
In a MapReduce application, the output of the map function is processed by the MapReduce framework and sent to the reduce function. This process is based on key-value pairs for sorting and grouping.
Options
- ATrue
- BFalse
How the community answered
(54 responses)- A76% (41)
- B24% (13)
Explanation
Option A is correct because MapReduce's core mechanism relies entirely on key-value pairs: the map function emits intermediate key-value pairs, the framework then sorts and groups all values by key (the "shuffle and sort" phase), and finally sends each unique key with its grouped values to the reduce function.
Option B is wrong because there is no alternative mechanism - sorting and grouping by key is not optional or configurable away; it is the fundamental contract of the MapReduce model, as defined by Google's original 2004 paper.
Memory tip: Think of MapReduce like a library card catalog. The Map phase writes index cards (key-value pairs), the framework sorts and stacks them alphabetically (shuffle & sort), and the Reduce phase processes each stack - you can't skip the sorting step and still have a functioning card catalog.
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