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

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 3

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

Question 4

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 5

Below is a sample document of 'orders' collection

Other-Image-2821600ab-2cee-4cd9-a321-aa3202108fcf

Options :

A : $project

Answer: A

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