MongoDB interview questions part 23
MongoDB interview questions part 23
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Total Questions: 20
1. The _____ JavaScript engine allows multiple JavaScript operations to execute at the same time.
Correct Answer is : V8
2. Point out the correct statement :
Correct Answer is : The map-reduce operation is composed of many tasks
3. If the ______ field for mapReduce has the sharded value, MongoDB shards the output collection using the _id field as the shard key.
Correct Answer is : $out
4. In MongoDB ______ ,mongos retrieves the results from each shard, performs a merge sort to order the results
Correct Answer is : 2
5. Point out the wrong statement :
Correct Answer is : None of the mentioned
6. Which of the following function follows the reduce method and modifies the output ?
Correct Answer is : finalize
7. __________ specifies global variables that are accessible in the map
Correct Answer is : scope
8. MongoDB converts the JavaScript objects emitted by the map function to ________ objects.
Correct Answer is : BSON
9. You can only use jsMode for result sets with fewer than 500,000 distinct key arguments to the mapper’s _______ function.
Correct Answer is : emit()
10. Which of the following mode defaults to false ?
Correct Answer is : jsMode
11. Which of the following members should be hidden ?
Correct Answer is : Delayed
12. Point out the wrong statement :
Correct Answer is : Hidden members cannot vote in replica set elections
13. __________ operations cannot guarantee that the data files do not change.
Correct Answer is : db.fsyncUnlock()
14. _______ may block reads, including those necessary to verify authentication.
Correct Answer is : db.fsyncLock()
15. Point out the correct statement :
Correct Answer is : Users may configure read preference on a per-connection basis to prefer that the read operations return results from the secondary members
16. ________ unlocks a mongod instance to allow writes and reverses the operation of a db.fsyncLock() operation.
Correct Answer is : db.fsyncUnlock()
17. Delayed members are a ________ or a running “historical” snapshot of the data set
Correct Answer is : “rolling backup”
18. Delayed members apply operations from the _______ on a delay.
Correct Answer is : oplog
19. In sharded clusters, delayed members have limited utility when the __________ is enabled.
Correct Answer is : Balancer
20. A delayed member has its priority equal to 0 and hidden equal to___________
Correct Answer is : TRUE
