MongoDB C100DBA Online Practice Questions and Exam Preparation

MongoDB C100DBA Online Questions & Answers

• Question 111:

  Which of the following is true about sharding?

  A. Creating a sharded key automatically creates an index on the collection using that key
  B. We cannot change a shard key directly/automatically once it is set up
  C. A sharded environment does not support sorting functionality since the documents lie on various mongod instances
  D. Sharding is enabled at the database level
  B. We cannot change a shard key directly/automatically once it is set up

• Question 112:

  What is the output of following two commands in MongoDB: db. posts. insert({n_id":l}) db.posts.insert({"_id":l})

  A. Two documents will be inserted with _id as 1
  B. MongoDB will automatically increment the _id of the second document as 2
  C. This will throw a duplicate key error
  D. It will insert two documents and throw a warning to the user
  C. This will throw a duplicate key error

• Question 113:

  Which of the following statements are true about the $match pipeline operator? Check all that apply.

  A. You should use it early as possible in the pipeline
  B. It can be used as many time as needed.
  C. It has a sintax similar to findQ commands.
  A. You should use it early as possible in the pipeline
  B. It can be used as many time as needed.
  C. It has a sintax similar to findQ commands.

• Question 114:

  The oplog (operations log) is a special capped collection that keeps a rolling record of all operations that modify the data stored in your databases. All the replica set members contain a copy of the oplog in the following collection:

  A. oplog.rs
  B. ..oplog.rs
  C. .oplog.rs
  D. local.oplog.rs
  D. local.oplog.rs

• Question 115:

  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 ratings array contains elements that in some combination satisfy the query conditions?

  A. db.inventory.find( { ratings: { $elemMatch: { $gte: 3, $lte: 6 } } } )
  B. db.inventory.find( { ratings: { $elemMatch: { $gt: 3, $lt: 6 }
  C. db.inventory.find( { ratings: { ratings.$: { $gt: 5, $lt: 9 } } } )
  D. db.inventory.find( { ratings: { ratings: { $gt: 5, $lt: 9 } } } )
  D. db.inventory.find( { ratings: { ratings: { $gt: 5, $lt: 9 } } } )

• Question 116:

  Below is a sample document in a given collection test.

  {

  a : 5, b : 3, c: 2, d : 1 >

  Given a compound index { a: 1, b:l, c:l, d:l}, Which of the below query will not use in- memory sorting? Select all valid.

  A. db.test.find( { a: 5, b: 3 } ).sort( { c: 1, d : 1 } )
  B. db.test.find( { a: 5, b: 3 } ).sort( { a: 1} )
  C. db.test.find( { a: 5, b: 3 } ).sort( { a: 1, b: 1, c: 1 > )
  D. db.test.find( { a: 5, b: 3 } ).sort( {c: 1 } )
  A. db.test.find( { a: 5, b: 3 } ).sort( { c: 1, d : 1 } )
  D. db.test.find( { a: 5, b: 3 } ).sort( {c: 1 } )

• Question 117:

  We can insert multiple documents in bulk using which of the following operations:

  A. initializeUnorderedBulk
  B. initializeUnorderedBulkOp
  C. initializeBulk
  D. initializeBulkOp
  B. initializeUnorderedBulkOp

• Question 118:

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

  A. specify {all: true} as the third parameter of update command
  B. updateAII instead of update
  C. specify {updateAII: true} as the third parameter of update command
  D. specify {multi : true} as the third parameter of update command
  D. specify {multi : true} as the third parameter of update command

• Question 119:

  MongoDB is a schema-less design.

  A. False
  B. True
  B. True

• Question 120:

  What does the following aggregate query perform?

  

  A. Fetches the posts with likes between 100 and 200 and sets their _id as null
  B. Groups the posts by number of likes (101, 102, 103.) by adding 1 every time
  C. Calculates the number of posts with likes between 100 and 200
  D. Fetches the posts with likes between 100 and 200, sets the _id of the first document as null and then increments it 1 every time
  C. Calculates the number of posts with likes between 100 and 200