[Aug-2023] Free C100DEV Exam Questions C100DEV Actual Free Exam Questions

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NEW QUESTION # 72
Select all true statements about query plans in MongoDB. (select 2)

• A. Query plans are cached so that plans don't have to be generated and compared with each other each time a query is executed.
• B. For a given query, each index in the collection generates at least one query plan.
• C. If there are no indexes for the query, the main stage in the query plan will be the COLLSCAN stage.

Answer: A,C

Explanation:
https://docs.mongodb.com/manual/core/query-plans/

NEW QUESTION # 73
Why is MongoDB using BSON instead of JSON to store data? Select all that apply.

• A. BSON supports more data types than JSON.
• B. BSON format is not human readable (BSON is machine-readable only).
• C. BSON simply means 'Binary JSON'.
• D. BSON contains metadata to describe a document/object.

Answer: A,B,C,D

Explanation:
https://www.mongodb.com/json-and-bson

NEW QUESTION # 74
Select true statements about index performance.

• A. For the fastest processing, we should make sure our indexes fit entirely in RAM.
• B. Indexes don't have to be completely stored in RAM, but permanent disk access to retrieve index information will have a performance impact.
• C. Indexes cannot decrease insert throughput.

Answer: A,B

Explanation:
https://www.mongodb.com/blog/post/performance-best-practices-indexing

NEW QUESTION # 75
There is a collection named products in MongoDB database. Your coworker wants to know how many products are in this collection (number of documents in the collection) from the United States. Which query should you use?

• A. db.products.find( { country: "USA" } ).count()
• B. db.products.find( country = "USA" ).count()
• C. db.products.find( { country: "USA" } )
• D. db.products.find( country == "USA" ).count()

Answer: A

Explanation:
https://docs.mongodb.com/manual/reference/method/db.collection.find/

NEW QUESTION # 76
Consider a many-to-many relationship observed between courses and the students enrolled in these courses. Which of the following are true about modeling this many-to-many relationship with the document model in MongoDB?

• A. The many-to-many relationship cannot be represented in MongoDB.
• B. Embedding students in courses duplicates student information.
• C. When using one collection for students and one collection for courses there is a need for an array of references in only one collection.
• D. Embedding students in courses still requires a separate collection to store all students (we may have students who are not enrolled in any course).

Answer: B,C,D

Explanation:
https://docs.mongodb.com/manual/applications/data-models-relationships/

NEW QUESTION # 77
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 } } We need to extract all movies from this collection where genres includes both 'Crime' and 'Mystery'. Which query should we use?

• A. db.movies.find( { genres: { $nin: ["Crime", "Mystery"] } } )
• B. db.movies.find( { genres: { $in: ["Crime", "Mystery"] } } )
• C. db.movies.find( { genres: { $all: ["Crime", "Mystery"] } } )
• D. db.movies.find( { genres: { $any: ["Crime", "Mystery"] } } )

Answer: C

Explanation:
https://docs.mongodb.com/manual/reference/operator/query/all/

NEW QUESTION # 78
You have the following configuration file: net: bindIp: localhost port: 27000 security: authorization: enabled.
You have to edit this file to use new directory as the dbPath: /var/mongodb/db Select correct Answer .

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

Answer: A

Explanation:
https://docs.mongodb.com/manual/reference/configuration-options/

NEW QUESTION # 79
You have the following index in a movies collection: { "title": 1, "imdb.rating": -1, "imdb.votes": -1, "type": 1 } Can the following query use the given index for both filtering and sorting?
db.movies.find( { "title": { "$lt": "M" } } ).sort( { "imdb.votes": -1 } )

• A. No
• B. Yes

Answer: A

Explanation:
No, this query does not use equality in the index prefix. When you use an index to filter and sort, the query must contain equality conditions on all prefix keys that precede the sort keys. Also, it skipped the next key in the "imdb.rating" prefix in the sort predicate. https://docs.mongodb.com/manual/indexes/

NEW QUESTION # 80
Suppose we have a shipwrecks collection with the following document structure: { _id: ObjectId("578f6fa2df35c7fbdbaed8ce"), feature_type: 'Wrecks - Visible', watlev: 'always dry', coordinates: [ -79.9469681, 9.3729954 ] } You ran the command below: db.shipwrecks.getIndexes() And you got the following output: [ { v: 2, key: { _id: 1 }, name: '_id_' }, { v: 2, key: { coordinates: '2dsphere' }, name: 'coordinates_2dsphere', '2dsphereIndexVersion': 3 } ] How can you remove the geospatial index on the coordinates field?

• A. db.shipwrecks.dropCollection('coordinates_2dsphere')
• B. db.shipwrecks.dropIndex('_id_')
• C. db.shipwrecks.dropIndex('coordinates_2dsphere')

Answer: C

Explanation:
https://docs.mongodb.com/manual/core/2dsphere/

NEW QUESTION # 81
We have the following indexes in a movies collection: { _id: 1 } { title: 1, year: 1 } Which of the following queries can be covered by one of the given indexes?

• A. db.movies.find( { genres: "Crime" }, { _id: 0, title: 1, year: 1, genres: 1 } )
• B. db.movies.find( { title: { $in: [ "Death Note", "The Immigrant" ] } }, { _id: 0, title: 1, year: 1 } )
• C. db.movies.find( { title: { $in: [ "Death Note", "The Immigrant" ] } }, { _id: 0, title: 1, year: 1, genres: 1 } )

Answer: B

Explanation:
No, this query would use the { title: 1, year: 1 } index, but it is projecting the genres field. https://docs.mongodb.com/manual/core/query-optimization/#covered-query

NEW QUESTION # 82
Which command do you use to display all indexes in routes collection?

• A. db.routes.dropIndex()
• B. db.routes.getIndexes()
• C. db.routes.dropIndex()
• D. db.routes.indexes()

Answer: B

Explanation:
https://docs.mongodb.com/manual/reference/method/db.collection.getIndexes/

NEW QUESTION # 83
We have the following index in a movies collection: { title: 1, genres: 1 } We want to insert the following document: { "title": "The Immigrant", "year": 1917, "genres": [ "Short", "Comedy", "Drama" ] } Select proper index entries.

• A. "The Immigrant", "Drama"
• B. "Short", "The Immigrant"
• C. "The Immigrant", "Short", "Comedy", "Drama"
• D. "Comedy", "The Immigrant"
• E. "The Immigrant", "Short"
• F. "The Immigrant", "Comedy"
• G. "Drama", "The Immigrant"

Answer: A

Explanation:
https://docs.mongodb.com/manual/indexes/

NEW QUESTION # 84
Which of the following commands will add a collection that is stored in JSON file to a MongoDB cluster?

• A. mongostore
• B. mongodump
• C. mongoexport
• D. mongoimport

Answer: D

Explanation:
https://docs.mongodb.com/database-tools/mongoimport/

NEW QUESTION # 85
Suppose you have a books collection with title field. Which of the following queries will return all books with a title ending in 'ian'?

• A. db.movies.find( { title: { $regex: /ian/ } } )
• B. db.movies.find( { title: { $regex: /.*ian$/ } } )
• C. db.movies.find( { title: { $regex: /.*ian/ } } )
• D. db.movies.find( { title: { $text: /.*ian$/ } } )

Answer: B

Explanation:
https://docs.mongodb.com/manual/reference/operator/query/regex/

NEW QUESTION # 86
Data modeling. You are considering the use of nesting or the references in your data model. Data read operations must be fast. Which option would be more appropriate?

• A. Use of nesting.
• B. Use of reference.

Answer: A

Explanation:
https://docs.mongodb.com/manual/core/data-modeling-introduction/

NEW QUESTION # 87
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