Free MongoDB C100DEV Exam Questions

Suppose you have a restaurants collection with the following document structure:

{

  _id: ObjectId("5eb3d668b31de5d588f42931"),

  address: {

    building: '6409',

    coord: [ -74.00528899999999, 40.628886 ],

    street: '11 Avenue',

    zipcode: '11219'

  },

  borough: 'Brooklyn',

  cuisine: 'American',

  grades: [

    {

      date: ISODate("2014-07-18T00:00:00.000Z"),

      grade: 'A',

      score: 12

    },

    {

      date: ISODate("2013-07-30T00:00:00.000Z"),

      grade: 'A',

      score: 12

    },

    {

      date: ISODate("2013-02-13T00:00:00.000Z"),

      grade: 'A',

      score: 11

    },

    { date: ISODate("2012-08-16T00:00:00.000Z"), 

      grade: 'A', 

      score: 2 },

    {

      date: ISODate("2011-08-17T00:00:00.000Z"),

      grade: 'A',

      score: 11

    }

  ],

  name: 'Regina Caterers',

  restaurant_id: '40356649'

}

You don't have any indexes so far. What will the query plan look like for the following query?

db.restaurants.find( { "cuisine": "American" } )

You are managing a MongoDB collection named orders, where each document represents an order. The documents contain the following fields:order_id (String): The unique identifier for the order.customer_name (String): The name of the customer who placed the order.total_amount (Number): The total amount of the order.status (String): The status of the order, which can be "pending," "shipped," or "delivered."items (Array of Strings): A list of items included in the order.You want to find all orders that meet the following criteria:The order has a total amount greater than $1000.The order status is either "pending" or "shipped."The order contains either "laptop" or "smartphone" in the list of items.Which of the following queries would return the correct documents?

A MongoDB collection named logs is used to store event data for a web application. The collection originally had indexes on the timestamp, user_id, and event_type fields to facilitate fast queries on these fields. Due to a recent data archiving strategy, you decide to remove the index on event_type to save storage space. However, after doing so, some queries on the logs collection have slowed down considerably, especially those filtering by event_type. What is the most likely ramification of deleting the index on the event_type field?

Suppose you're designing a MongoDB database for an online ticket booking system where millions of users can concurrently book tickets for various events. To maintain data consistency, you need to ensure that only one user can book a specific seat for an event at a time. Which MongoDB feature would you use to ensure data consistency in this high-concurrency situation?