MongoDB MongoDB Certifications C100DBA Questions & Answers

• Question 51:

  Which of the following is a valid insert statement in mongodb? Select all valid.

  A. db.test.push({x:2,y:"apple"})

  B. db.test.insert?quot;";:2,";";";appl";})

  C. db.test.insert({x:2,y:"apple"})

  D. db.test.insert({x:2},{y:"apple"})

  Correct Answer: BC

• Question 52:

  Which mongodb tool is used to report details on number of database operations in MongoDB?

  A. mongostat

  B. mongotop

  C. mongorestore

  D. mongodump

  Correct Answer: A

• Question 53:

  Consider the following example document from the sample collection. All documents in this collection have the same schema.

  

  Which of the following queries will replace this with the document.

  

  A. db.sample.update( { "_id" : 3 } , { "$set" : { "_id" : 7 , "c" : 4 > > )

  B. db.sample.update( { "_id" : 3 > , { "_id" : 7 , "c" : 4 > , { "justOne" : true > ) / This operation cannot be done with a single query.

  C. db.sample.update( { "_id" : 3 > , { "_id" : 7 , "c" : 4 , { "$unset" : [ "a" , "b" ] } } )

  D. db.sample.update( { "_id" : 3 > , { "_id" : 7 , "c" : 4 > )

  Correct Answer: C

• Question 54:

  As per the aggregation pipeline optimization concepts, if you have a $sort followed by a $match:

  A. Providing these parameters in any order does not impact the performance

  B. $sort moves before $match

  C. MongoDB does not do any movements by default and will use the order provided

  D. $match moves before $sort

  Correct Answer: D

• Question 55:

  The MongoDB explain() method does not support which of the following verbosity mode:

  A. executionStats

  B. queryPlanner

  C. customExecutionStats

  D. allPlansExecution

  Correct Answer: C

• Question 56:

  Which of the following aggregation commands in MongoDB does not support sharded collections?

  A. mapReduce

  B. group

  C. aggregate

  D. All of the above

  Correct Answer: B

• Question 57:

  Which of the following operator can be used to control the number of items of an array that a query returns?

  A. $ elemMatch

  B. $slice

  C. $

  D. MongoDB does not support partial retrieval of items from an array

  Correct Answer: B

• Question 58:

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

  A. $ elemMatch

  B. $slice

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

  D. $

  Correct Answer: D

• Question 59:

  Which is the correct order (lowest to highest) in which MongoDB compares the BSON types?

  A. Number, Null, String and Object

  B. Null, Number, Object and String

  C. Null, Number, String and Object

  D. String, Null, Number and Object

  Correct Answer: C

• Question 60:

  Consider the following document from the products collection: What does the following query using $elemMatch return? db.products.find( { product_code: "345678" }, { variations: { $elemMatch: { size: ^L^ } } } )

  

  A. Returns the complete document but retrieves only the size field from the array

  B. Returns the document but with only one element in the variations array (corresponding to size L)

  C. Returns the complete document since MongoDB does not support partial array retrieval

  D. Returns the complete document but retrieves only the size field from the array and also with only one element in the variations array (corresponding to size L)

  Correct Answer: B