MongoDB Online Quiz
Following quiz provides Multiple Choice Questions (MCQs) related to MongoDB Framework. You will have to read all the given answers and click over the correct answer. If you are not sure about the answer then you can check the answer using Show Answer button. You can use Next Quiz button to check new set of questions in the quiz.
Q 1 - In a collection that contains 100 post documents, what does the following command do?
db.posts.find().skip(5).limit(5)
A - Skip and limit nullify each other. Hence returning the first five documents.
B - Skips the first five documents and returns the sixth document five times
C - Skips the first five documents and returns the next five
D - Limits the first five documents and then return them in reverse order
Answer : C
Explanation
The skip and limit functions are applies linearly and hence it will first skip documents 1-5, and then return documents 6-10.
Q 2 - Which of the following replica sets vote in the election of a primary replica set?
Answer : D
Explanation
All members of a replica set, unless the value of votes is equal to 0, vote in elections. This includes all delayed, hidden and secondary-only members.
Q 3 - In our posts collection, which command can be used to find all the posts whose author names begin lie between “A” and “C” in dictionary order?
A - db.posts.find( { post_author : { $gte : "A" , $lte : "C" } } );
B - db.posts.find( { post_author : { $gte : "C" , $lte : "A" } } );
C - db.posts.find( { post_author : { $gt : "A" , $lt : "C" } } );
Answer : A
Explanation
The $gt, $lt and related operators can be applied for string manipulations too. They work in the same manner as they would work on numeric values.
Q 4 - What does the following query do when performed on the posts collection?
db.posts.update({_id:1},{$set:{Author:”Tom"}})
B - Adds a new field Author in the searched collection if not already present
C - Updates only the Author field of the document with _id as 1
Answer : D
Explanation
$set sets the specific fields in the matched documents or adds them as a new field if not already present.
Q 5 - Which type of indexes does MongoDB support?
Answer : D
Explanation
MongoDB supports all of the above mentioned indexes.
Q 6 - Which of the following collections are used by MongoDB to store GridFS data?
Answer : A
Explanation
GridFS stores files in two collections: chunks stores the binary chunks and files stores the file’s metadata.
Q 7 - The following aggregation option is used to specify the specific fields that needs to be passed to the next stage of the aggregation pipeline:
Answer : B
Explanation
The $project operator passes along the documents with only the specified fields to the next stage in the pipeline. The specified fields can be existing fields from the input documents or newly computed fields.
Q 8 - Which of the following aggregation commands in MongoDB does not support sharded collections?
Answer : C
Explanation
The group command in MongoDB groups documents in a collection by the specified key and performs simple aggregation functions, such as computing counts and sums. It is the most basic one and does not support such sharding concepts.s
Q 9 - In a sharded replica set environment, w defines the level and kind of write concern. Which of the following values of w specifies to return success only after a majority of voting members have acknowledged?
Answer : B
Explanation
For replica sets, if you specify the special majority value to w option, write operations will only return successfully after a majority of the voting members of the replica set have acknowledged the write operation.
Q 10 - Which of the following operator can be used to control the number of items of an array that a query returns?
D - MongoDB does not support partial retrieval of items from an array
Answer : C
Explanation
The $slice operator controls the number of items of an array that a query returns.
