MongoDB C100DEV 問題集 : MongoDB Certified Developer Associate Exam

Given a movies collection where each document has the following structure: { _id: ObjectId("573a1391f29313caabcd9264"), genres: [ 'Romance', 'Drama' ], title: 'The Divorcee', languages: [ 'English', 'French' ], year: 1930, imdb: { rating: 6.9, votes: 1740, id: 20827 }, countries: [ 'USA' ] } Which of the following queries will find all movies that have exactly 5 languages?

• A. db.movies.find( { languages: 5 } )
• B. db.movies.find( { languages: { $size: 5 } } )
• C. db.movies.find( { languages: { $eq: 5 } } )
• D. db.movies.find( { languages: { $gt: 5 } } )

You have to create a simple configuration file for mongod instance. Here are the requirements of your mongod instance: * stores data files in /var/mongo/db * listens to connection from localhost * runs on port 27000 * uses authentication Which of the following configuration file meet these requirements?

• A. storage:
  dbPath: /var/mongodb/db
  net:
  bindIp: localhost
  port: 27000
  security:
  authorization: enabled
• B. storage:
  dbPath: /var/mongodb/db
  security:
  authorization: enabled
• C. storage:
  dbPath: /var/mongodb/db
  net:
  bindIp: localhost
  port: 27000
• D. net:
  bindIp: localhost
  port: 27000
  security:
  authorization: enabled

We have an accounts collection with the following document structure:
{ _id: ObjectId("61af47c6e29861661d063714"), account_id: 1010, type: 'investment', limit: 1000000 }
And the following query:
db.accounts.find({ "$or": [ { "type": { "$in": [ "investment", "derivatives" ] } }, { "limit": { "$gt": 500000 } } ] })
Which of the documents below will be retrieved by this query?

• A. { _id: ObjectId("61af47c6e29861661d067825"), account_id: 7355, type: 'commodity', limit: 500000 }
• B. { _id: ObjectId("61af47c6e29861661d063715"), account_id: 4336, type: 'derivatives', limit: 100000 }
• C. { _id: ObjectId("61af47c6e29861661d063714"), account_id: 1010, type: 'investment', limit: 1000000 }
• D. { _id: ObjectId("61af47c6e29861661d063357"), account_id: 1752, type: 'commodity', limit: 1000 }

We have a movies collection with the following document structure: { _id: ObjectId("573a1390f29313caabcd6223"), genres: [ 'Comedy', 'Drama', 'Family' ], title: 'The Poor Little Rich Girl', released: ISODate("1917-03-05T00:00:00.000Z"), year: 1917, imdb: { rating: 6.9, votes: 884, id: 8443 } }, { _id: ObjectId("573a13e3f29313caabdc08a4"), genres: [ 'Horror', 'Thriller' ], title: 'Mary Loss of Soul', year: 2014, imdb: { rating: '', votes: '', id: 2904798 } } We need to use Aggregation Framework to calculate the following aggregates: -> average imdb rating -> minimum imdb rating -> maximum imdb rating Expected output: [ { _id: null, avg_rating: 6.6934040649367255, min_rating: 1.6, max_rating: 9.6 } ] Please note that some documents have "" (empty string) for the field "imdb.rating". Exclude these documents before aggregation. Which pipeline should you use?

• A. [{ $group: { _id: null, avg_rating: { $avg: "$imdb.rating" }, min_rating: { $min: "$imdb.rating" }, max_rating: { $max: "$imdb.rating" } } }]
• B. [{ $match: { "imdb.rating": { $ne: "" } } }, { $group: { _id: null, avg_rating: { $avg: "imdb.rating" }, min_rating: { $min: "imdb.rating" }, max_rating: { $max: "imdb.rating" } } }]
• C. [{ $match: { "imdb.rating": { $ne: "" } } }, { $group: { _id: null, avg_rating: { $avg: "$imdb.rating" }, min_rating: { $min: "$imdb.rating" }, max_rating: { $max: "$imdb.rating" } } }]
• D. [{ $match: { "imdb.rating": { $ne: "" } } }, { $group: { _id: null, avg_rating: { avg: "$imdb.rating" }, min_rating: { min: "$imdb.rating" }, max_rating: { max: "$imdb.rating" } } }]

Suppose you have an accounts collection in your database. Only the following documents are stored in this collection: { _id: ObjectId("61af47c6e29861661d063714"), account_id: 1010, type: 'investment', limit: 2000000 }, { _id: ObjectId("61af47c6e29861661d063715"), account_id: 4336, type: 'derivatives', limit: 100000 }, { _id: ObjectId("61af47c6e29861661d063716"), account_id: 4336, type: 'commodity', limit: 1000 }, { _id: ObjectId("61af47c6e29861661d067825"), account_id: 7355, type: 'commodity', limit: 500000 }, { _id: ObjectId("61b1bde1ceb6f770f56b0cd9"), account_id: 4915, type: 'investment', limit: 2000000 } How many documents will be returned in response to the following aggregation pipeline? [{ $group: { _id: "$type", number_of_accounts: { $sum: 1 } }}, { $match: { number_of_accounts: { $gt: 1 } }}]

• A. 0
• B. 3
• C. 1
• D. 2