mongodb

What does the following MongoDB command return?

db.posts.find( { likes : { $gt : 100 }, likes : { $lt : 200 } } );

• Posts with likes greater than 100 but less than 200

• Posts with likes greater than or equal to 100 but less than or equal to 200

• Posts with likes less than 200

• Will return syntax error

What does the output x of the following MongoDB aggregation query result into:

db.posts.aggregate( [ { $group: { _id: "$author", x: { $sum: �$likes� } } } ] )

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

• Number of posts by an author

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

• Sum of likes on all the posts by all the authors

The _______ operator can be used to identify an element in the array to be updated without explicitly specifying the position of the element.

• $

• $elemMatch

• $slice

• Updating an array field without knowing its index is not possible.

NoSQL databases is used mainly for handeling large volumes of ........... data

• structured

• unstructured

• semi-structured

• None of above

What is supported by MongoDB?

• BSON

• JSON

• XML

Which of the following dynamic schema phenomenon is made easier for the 

application by MongoDB?

• Polymorphism

• Encapsulation

• Inheritance

• None of above

Which of the following commands will find all the posts that have been tagged as tutorial.

• db.posts.find( { tags : "tutorial" } );

• db.posts.find( { tags : ["tutorial"] } );

• db.posts.find( { $array : {tags: "tutorial"} } );

• db.posts.findInArray( { tags : "tutorial" } );

Consider that our posts collection contains an array field called tags that contains tags that the user enters.

What does the following command return:

db.posts.find( { 'tags.0': �tutorial� } )

• All the posts whose tags array contains tutorial

• All the posts which contains only one tag element in the tag array

• All the posts having the first element of the tags array as tutorial

• All the posts which contains 0 or more tags named tutorial

Consider that the posts collection contains an array called ratings which contains ratings given to the post by various users in the following format:

Which of the following query will return all the documents where the array ratings contains at least one element between 3 and 6?

• db.inventory.find( { ratings: { $elemMatch: { $gt: 3, $lt: 6 } } } )

• db.inventory.find( { ratings: { ratings: { $gt: 5, $lt: 9 } } } )

• db.inventory.find( { ratings: { ratings.$: { $gt: 5, $lt: 9 } } } )

• db.inventory.find( { ratings: { $elemMatch: { $gte: 3, $lte: 6 } } } )

Which option should be used to update all the documents with the specified condition in the MongoDB query?

• updateAll instead of update

• specify {multi : true} as the third parameter of update command

• specify {all: true} as the third parameter of update command

• specify {updateAll: true} as the third parameter of update command