Free Online MongoDB C100DEV Practice Test

A collection called players contains the following documents:

[

  { _id: 1, user: 'Tom', scores: [ 23, 56, 3, 52, 62 ], bonus: 5 },

  { _id: 2, user: 'Jane', scores: [ 42, 50, 10 ], bonus: 3 }

]

You want to add additional fields to each document:

-> total_score (sum of the scores Array)

-> avg_score (average score in scores Array)

-> total_score_with_bonus (total_score + bonus)

Expected output:

[

  {

    _id: 1,

    user: 'Tom',

    scores: [ 23, 56, 3, 52, 62 ],

    bonus: 5,

    total_score: 196,

    avg_score: 39.2,

    total_score_with_bonus: 201

  },

  {

    _id: 2,

    user: 'Jane',

    scores: [ 42, 50, 10 ],

    bonus: 3,

    total_score: 102,

    avg_score: 34,

    total_score_with_bonus: 105

  }

]

Which query do you need to use?

What is the built-in database called config in MongoDB for?

Which of the following queries can use an index on the title field? (select 2)

Suppose you are connected to mongod instance that is already running on port 27000 as admin user. You have to create a new user for an application that has the readWrite role. Use the db.createUser() command to create a user for data analysis.

The requirements for this user are:

-> role: read on esmartdata database

-> username: dataScientist

-> password: ds123sci456

Which command should you use?

Use case: e-learning platform

Which of the following scenarios is the best candidate to use the Extended Reference Pattern to avoid additional reads by joins/lookups?