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Question 1 Selectable Answer

We have an accounts collection with only one document:
{
_id: 54657,
account_id: 557378,
products: [ 'InvestmentStock', 'Commodity', 'CurrencyService' ]
}
We need to use Aggregation Framework to unwind the products Array to obtain new documents with
only one product per document (see below).
Expected output:
[
{ _id: 54657, account_id: 557378, products: 'InvestmentStock' },
{ _id: 54657, account_id: 557378, products: 'Commodity' },
{ _id: 54657, account_id: 557378, products: 'CurrencyService' }
]
Which pipeline should you use?

A. [{ $facet: { path: "$products", } }]
B. [{ $unwind: { path: "$products", } }]
C. [{ $unset: { path: "$products", } }]
D. [{ $project: { path: "$products", } }]

Answer:
Explanation:
https://docs.mongodb.com/manual/reference/operator/aggregation/unwind/

Question 2 Selectable Answer

Which of the following commands will delete a collection named restaurants?

A. db.restaurants.dropCollection()
B. db.restaurants.delete()
C. db.restaurants.remove()
D. db.restaurants.drop()

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

Question 3 Selectable Answer

Select all true statements regarding to the role of fields and values in a MongoDB document. (select 2)

A. A field is a unique identifier for a specific data point.
B. You can have duplicate field names within the same level of a single document.
C. Values don't need to be attached to fields and can be standalone data points.
D. Each field has a value associated with it.

Answer:
Explanation:
https://docs.mongodb.com/manual/core/document/

Question 4 Selectable Answer

Which of the following commands will successfully insert exactly two new documents into an empty companies collection?

A. db.companies.insertMany([ {"_id": 1, "name": "Facebook"}, {"_id": 1, "name": "Twitter"}, {"_id": 2, "name": "Tesla"} ], {"ordered": false})
B. db.companies.insertMany([ {"_id": 1, "name": "Facebook"}, {"_id": 1, "name": "Twitter"}, {"_id": 2, "name": "Tesla"} ])
C. db.companies.insertMany([ {"_id": 1, "name": "Facebook"}, {"_id": 2, "name": "Twitter"} ]) D, db.companies.insertMany([ {"_id": 1, "name": "Facebook"}, {"_id": 2, "name": "Twitter"}, {"_id": 2, "name": "Tesla"} ])
D. db.companies.insertMany([
E. {"name": "Facebook"},
F. {"name": "Twitter"}
G. ])

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

Question 5 Selectable Answer

Which of the following methods executes a database command? (mongo shell)

A. db.execute({ <command> })
B. db.ommand({ <command> })
C. db.runCommand({ <command> })
D. db.runThisCommand({ <command> })

Answer:
Explanation:
https://docs.mongodb.com/manual/reference/method/db.runCommand/

Question 6 Selectable Answer

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?

A. db.movies.find( { "imdb.rating": 8, "title": "James Bond" } ).sort( { "imdb.votes": -1 } )
B. Yes
C. No

Answer:
Explanation:
Yes, this query can use the index prefix. The order of the fields in the query predicate does not matter.
Since both "imdb.rating" and "title" are part of an index prefix, this query can use the index for an equality condition.
https://docs.mongodb.com/manual/indexes/

Question 7 Selectable Answer

Suppose you insert the following documents into companies collection:
db.companies.insertMany([
{"_id": 1, "name": "Facebook"},
{"_id": 1, "name": "Twitter"},
{"_id": 2, "name": "Tesla"},
{"_id": 3, "name": "Amazon"}
], {"ordered": false})
Select all true statements about this operation. (select 3)

A. Two documents will be inserted into the collection.
B. This insert is unordered.
C. Three documents will be inserted into the collection.
D. MongoDB will insert each document with a unique _id value into the collection.
E. One document will be inserted into the collection.

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

Question 8 Selectable Answer

What does it command do in the mongo shell?

A. Iterates through the cursor results.
B. Terminates the current query execution.
C. it is not a mongo shell command.
D. Displays cluster statistics.

Answer:

Question 9 Selectable Answer

Suppose you have a companies collection in your database. Only the following documents are stored in
this collection:
{
_id: ObjectId("52cdef7c4bab8bd675297da4"),
name: 'Powerset',
category_code: 'search',
founded_year: 2006
},
{
_id: ObjectId("52cdef7c4bab8bd675297da5"),
name: 'Technorati',
category_code: 'advertising',
founded_year: 2002
},
{
_id: ObjectId("52cdef7c4bab8bd675297da7"),
name: 'AddThis',
category_code: 'advertising',
founded_year: 2004
},
{
_id: ObjectId("52cdef7c4bab8bd675297da8"),
name: 'OpenX',
category_code: 'advertising',
founded_year: 2008
},
{
_id: ObjectId("52cdef7c4bab8bd675297daa"),
name: 'Sparter',
category_code: 'games_video',
founded_year: 2007
},
{
_id: ObjectId("52cdef7c4bab8bd675297dac"),
name: 'Veoh',
category_code: 'games_video',
founded_year: 2004
},
{
_id: ObjectId("52cdef7c4bab8bd675297dae"),
name: 'Thoof',
category_code: 'web',
founded_year: 2006
}
What is the default sort order in the result set returned in response to the following query?

A. db.companies.aggregate( [ { "$sortByCount": "$category_code" } ] )
B. ascending
C. descending

Answer:
Explanation:
https://docs.mongodb.com/manual/reference/operator/aggregation/sortByCount/

Question 10 Selectable Answer

Select all options when you should deploy a MongoDB deployment with security enabled.

A. Deployment of the development environment.
B. Deployment of the evaluation environment.
C. Deployment of the staging environment.
D. Deployment of the production environment.

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

Question 11 Selectable Answer

You have the following config file:
storage:
dbPath: /data/db
systemLog:
destination: file
path: /var/log/mongod.log
net:
bindIp: localhost,192.168.168.62
security:
keyFile: /var/pki/keyfile
processManagement:
fork: true
Select all the directories that MongoDB must have access to

A. /var/log
B. /data/db
C. /var/pki

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

Question 12 Selectable Answer

Which of the following statements are true about the mongo shell? Check all that apply.

A. Mongo shell is a fully functioning JavaScript interpreter (which means that we can create things like JavaScript variables and functions in mongo shell).
B. Mongo shell allows us to interact with MongoDB instance without using GU
C. The mongo shell doesn't return documents in sorted order by default.
D. You can get a sorted set of documents by using the sort() method.

Answer:
Explanation:
https://docs.mongodb.com/manual/reference/mongo-shell/

Question 13 Selectable Answer

There is a gamers collection in your database with the following document structure:
{ _id: 1, level: 15, is_active: true },
{ _id: 2, level: 14, is_active: true },
{ _id: 3, level: 7, is_active: false }
How do you increase the value of the level field by 20 for a player with id = 3?

A. Expected result:
B. { _id: 1, level: 15, is_active: true },
C. { _id: 2, level: 14, is_active: true },
D. { _id: 3, level: 27, is_active: false }
E. db.gamers.update( { _id: 3 }, { $inc: { level: 20 } } )
F. db.gamers.update( { _id: 3 }, { $set: { level: 20 } } )
G. db.gamers.update( { _id: 3 }, { $unset: { level: 20 } } )

Answer:
Explanation:
https://docs.mongodb.com/manual/reference/operator/update/inc/

Question 14 Selectable Answer

Let's consider a replica set of 3 nodes that experiences a network outage. Select true statement.

A. When two nodes go down in a three-node replica set, the third node becomes a primary.
B. When two nodes go down in a three-node replica set, the third node becomes a secondary regardless of whether it started as a primary.

Answer:
Explanation:
https://docs.mongodb.com/manual/replication/#replication

Question 15 Selectable Answer

Which cursor method should you use to get information about the query plan?

A. cursor.hint()
B. cursor.explain()
C. cursor.map()

Answer:
Explanation:
https://docs.mongodb.com/manual/reference/method/cursor.explain/

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