Question

Point out the correct statement.

(a) Scrunch’s Java API is centered around three interfaces that represent distributed datasets

(b) All of the other data transformation operations supported by the Crunch APIs are implemented in terms of three primitives

(c) A number of common Aggregator<V> implementations are provided in the Aggregators class

(d) All of the mentioned

I have been asked this question in an interview.

This intriguing question originated from Crunch with Hadoop topic in portion Apache Spark, Flume, Lucene, Hama, HCatalog, Mahout, Drill, Crunch and Thrift of Hadoop

Answer 1

Correct choice is (c) A number of common Aggregator<V> implementations are provided in the Aggregators class

To explain I would say: PGroupedTable provides a combine values operation that allows a commutative and associative Aggregator to be applied to the values of the PGroupedTable instance on both the map and reduce sides of the shuffle.