Point out the correct statement.(a) The read phase takes a exclusive lock(b) The map-reduce operation is composed of many tasks(c) Prior to version 3, JavaScript code executed in a single thread(d) All of the mentionedThis question was addressed to me during an interview for a job.My question comes from Map-Reduce and Sharded Collections in chapter Aggregation Concepts and Aggregation Mechanics of MongoDB

Point out the correct statement.(a) The read phase takes a exclusive l

1.	Point out the correct statement.(a) The read phase takes a exclusive lock(b) The map-reduce operation is composed of many tasks(c) Prior to version 3, JavaScript code executed in a single thread(d) All of the mentionedThis question was addressed to me during an interview for a job.My question comes from Map-Reduce and Sharded Collections in chapter Aggregation Concepts and Aggregation Mechanics of MongoDB
Answer» Correct answer is (b) The MAP-reduce operation is composed of many tasks Easiest explanation: It includes reads from the input collection, executions of the map function, executions of the reduce function, writes to a temporary collection during PROCESSING, and writes to the OUTPUT collection.

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