For each intermediate key, each reducer task can emit:

Question

Options

• AAs many final key-value pairs as desired.
• BAs many final key-value pairs as desired, but they must have the same type as the intermediate
• CAs many final key-value pairs as desired, as long as all the keys have the same type and all the values
• DOne final key-value pair per value associated with the key; no restrictions on the type.
• EOne final key-value pair per key; no restrictions on the type.

• A
  11% (2)
• B
  11% (2)
• C
  72% (13)
• E
  6% (1)

Explanation

Reducer reduces a set of intermediate values which share a key to a smaller set of values. Reducing lets you aggregate values together. A reducer function receives an iterator of input values from an input list. It then combines these values together, returning a single output value.

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