Free MongoDB C100DEV Exam Questions

You manage a MongoDB collection called inventory that stores documents for a store's inventory. Each document has the fields item, category, and quantity. You want to ensure that an item is always present in the collection, even if it needs to be inserted. Specifically, if the item "notebook" in the "Stationery" category does not exist, it should be inserted with a quantity of 50. If it does exist, its quantity should be updated to 50. You plan to use the following command:

db.inventory.updateOne(

  { "item": "notebook", "category": "Stationery" },

  { $set: { "quantity": 50 } },

  { upsert: true }

)

What will happen after executing this command if there is no "notebook" item in the "Stationery" category in the inventory collection?

In your database there is a collection named companies with the following document structure:

{

  name: 'Wize',

  relationships: [

    {

      is_past: false,

      title: 'Head of Product',

      person: {

        first_name: 'Ethan',

        last_name: 'Smith',

        permalink: 'ethan-smith'

      }

    },

    {

      is_past: true,

      title: 'Director, Business Development',

      person: {

        first_name: 'Stephanie',

        last_name: 'Quay',

        permalink: 'stephanie-quay'

      }

    },

    {

      is_past: true,

      title: 'Sr. Engineer',

      person: {

        first_name: 'Stefan',

        last_name: 'Antonowicz',

        permalink: 'stefan-antonowicz'

      }

    }

  ]

}

Which of the following queries should you use to extract all companies that have "Co-Founder" title in relationships field (Array)?

As a MongoDB Developer, you are tasked with optimizing a MongoDB database. Your collection has documents with the following structure:

{

  "_id": ObjectId(),

  "user_id": Number,

  "user_data": {

    "name": String,

    "email": String,

    "phone": String,

    "address": {

      "city": String,

      "state": String,

      "country": String

    }

  },

  "transactions": [

    {

      "transaction_id": Number,

      "amount": Number,

      "date": Date

    }

  ]

}

The application frequently queries for the total transaction amount for users based on the city. Which index should you create to optimize the performance of these queries?