Question 1

Which of the following commands can cause the database to be locked?

Options :

A : All of the above

B : Inserting data

C : Map-reduce

D : Issuing a query

Answer: A

Question 2

What does the output x of the following MongoDB aggregation query result into; db.posts.aggregate( [ { $group: { _id; '$author', x: { $sum: $likes } } } ] )

Options :

A : Average of likes on all the posts of an author, grouped by author

B : Number of posts by an author

C : Sum of likes on all the posts by all the authors

D : Sum of likes on all the posts by an author, grouped by author

Answer: D

Question 3

You perform the following operation in the shell: db.foo.insert( { } ); What gets inserted?

Options :

A : A document will be inserted with the same _id as the last document inserted

B : A document that matches the collection-s existing schema, but with null fields

C : A document with an _id assigned to be an Objectld

D : An empty document

E : No document will be inserted; an error will be raised

Answer: C

Question 4

'mongoimport' command is used for

Options :

A : Batch data insertion

B : None of the above

C : Multiple command import

D : Multiple command insertion

Answer: A

Question 5

Which option can be used with update command so that a new document gets created if no matching document is found based on the query condition?

Options :

A : upsert command instead of update command

B : This has to be handled in application code (Node.js, PHP, JAVA, C#, etc.) and cannot be handled in mongo shell query

C : {update: true, insert: true} as the third parameter of update command

D : Specify {upsert : true } as the third parameter of update command

Answer: D