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 - Which of the following is correct explanation of MongoDB processes?

A - mongod.exe is the shell process and mongo.exe is the actual database process

B - mongo.exe is the shell process and mongod.exe is the actual database process

C - mongos.exe is the MongoDB server process needed to run database

D - mongodump.exe can be used to import database backup dump

Answer : B

Explanation

The core components in the MongoDB package are: mongod, the core database process; mongos the controller and query router for sharded clusters; and mongo the interactive MongoDB Shell.

Q 2 - What is the output of the following program?

Answer : A

Explanation

In the default configuration, MongoDB writes data to the main data files on disk every 60 seconds.

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" } } );

D - This type of search is not supported by MongoDB. $lt and $gt operators are applicable only for numeric values.

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},{Title:This is post with ID 1"})

A - Updates the Title of the post

B - Updating a document is possible only with $set

C - Replaces the complete document with _id as 1 with the document specified in second parameter

D - Syntax error

Answer : C

Explanation

Updating a document without using $set replaces the entire document with whatever document is specified in second parameter.

Q 5 - Which of the following operator can be used to limit the number of documents in an array field of a document after an update is performed?

A - $push along with $each, $sort and $slice

B - $removeFromSet

C - $arrayLimit

D - None of the above

Answer : A

Explanation

You can iterate over all the array elements using $each, slice them using $slice and then push them back to the document using $push.

Q 6 - What is the equivalent command in MongoDB for the following SQL query?

SELECT * FROM posts WHERE author like "%john%"

A - db.posts.find( { author: /john/ } )

B - db.posts.find( { author: {$like: /john/} } )

C - db.posts.find( { $like: {author: /john/} } )

D - db.posts.find( { author: /^john^/ } )

Answer : A

Explanation

db.posts.find( { author: /john/ } )

Q 7 - What is the minimum sensible number of voting nodes to a replica set?

Answer : B

Explanation

The minimum number of sensible number of voting nodes is 3.

Q 8 - What is a replica set node which does not maintain its own data but exists only for voting purpose called?

Answer : B

Explanation

We may add an extra mongod instance to a replica set as an arbiter. Arbiters do not maintain a data set. Arbiters only exist to vote in elections. If your replica set has an even number of members, add an arbiter to obtain a majority of votes in an election for primary. Arbiters do not require dedicated hardware

Q 9 - Which of the tags in a replica set configuration specify the operations to be read from the node with the least network latency?

A - primaryPreferred

B - secondaryPreferred

C - nearest

D - netLatency

Answer : C

Explanation

Operations read from member of the replica set with the least network latency, irrespective of the member�s type.

Q 10 - What does the following $slice query return using the following command?

   
db.posts.find( {}, { comments: { $slice: [ -10, 5 ] } } )

A - Returns 5 comments, beginning with the last 10 items

B - Returns 10 comments, beginning with the first

C - Returns 10 comments, beginning with the last

D - Returns 5 comments, beginning with the first 10 items

Answer : A

Explanation

The $slice operation selects the document collection identified by a field named field that holds value and returns the number of elements specified by the value of count from the array stored in the array field.

mongodb_questions_answers.htm