MongoDB Questions and Answers – Data Model Examples and Patterns

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This set of MongoDB Multiple Choice Questions & Answers (MCQs) focuses on “Data Model Examples and Patterns”.

1. Which of the following relationship uses references to describe documents between connected data?
a) One-to-One Relationships with Embedded Documents
b) One-to-Many Relationships with Embedded Documents
c) One-to-Many Relationships with Document References
d) None of the mentioned
View Answer

Answer: b
Explanation: One-to-Many Relationships with document references presents a data model that uses references to describe one-to-many relationships between documents.

2. Point out the correct statement.
a) One-to-One Relationships with embedded documents presents a data model that uses embedded documents to describe one-to-one relationships between connected data
b) One-to-One Relationships with document references presents a data model that uses embedded documents to describe one-to-one relationships between connected data
c) One-to-Many Relationships with embedded documents presents a data model that uses embedded documents to describe one-to-one relationships between connected data
d) All of the mentioned
View Answer

Answer: a
Explanation: One-to-Many Relationships with embedded documents presents a data model that uses embedded documents to describe one-to-many relationships between connected data.

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3. If the address data is frequently retrieved with the name information, how will you modify the following schema representing one to one relationship with referencing?

{
   _id: "joe",
   name: "Joe Bookreader"
}

{
   patron_id: "joe",
   street: "123 Fake Street",
   city: "Faketon",
   state: "MA",
   zip: "12345"
}

a)

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 {
   _id: "joe",
   name: "Joe Bookreader",
   address: {
              street: "123 Fake Street",
              city: "Faketon",
              state: "MA",
              zip: "12345"
            }
} 

b)

 {
   _id: "joe",
   name: "Joe Bookreader",
   address-> {
              street: "123 Fake Street",
              city: "Faketon",
              state: "MA",
              zip: "12345"
            }
} 

c)

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 {
   _id: "joe",
   name: "Joe Bookreader",
   address:: {
              street: "123 Fake Street",
              city: "Faketon",
              state: "MA",
              zip: "12345"
            }
} 

d) All of the mentioned
View Answer

Answer: a
Explanation: With the embedded data model, your application can retrieve the complete patron information with one query.

4. Which of the following is used to avoid the repetition of data in MongoDB schema?
a) DeReferences
b) References
c) Cursor
d) Collectors
View Answer

Answer: b
Explanation: When using references, the growth of the relationships determine where to store the reference.

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5. Point out the wrong statement.
a) Decisions that affect how you model data can affect application performance and database capacity
b) Collections do enforce document structure
c) Data in MongoDB has a flexible schema
d) None of the mentioned
View Answer

Answer: b
Explanation: Collections do not enforce document structure.

6. What would be the more optimal schema to embed the address data entities in the patron data for following schema representing one to many relationships?

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{
   _id: "joe",
   name: "Joe Bookreader"
}

{
   patron_id: "joe",
   street: "123 Fake Street",
   city: "Faketon",
   state: "MA",
   zip: "12345"
}

{
   patron_id: "joe",
   street: "1 Some Other Street",
   city: "Boston",
   state: "MA",
   zip: "12345"
} 

a)

{
   _id: "joe",
   name: "Joe Bookreader",
   addresses: [
                {
                  street: "123 Fake Street",
                  city: "Faketon",
                  state: "MA",
                  zip: "12345"
                },
                {
                  street: "1 Some Other Street",
                  city: "Boston",
                  state: "MA",
                  zip: "12345"
                }
              ]
 } ?

b)

{
   _id: "joe",
   name: "Joe Bookreader",
   addresses: [
                {
                  street: "123 Fake Street",
                  city: "Faketon",
                  state: "MA",
                  zip: "12345"
                },
                [
                  street: "1 Some Other Street",
                  city: "Boston",
                  state: "MA",
                  zip: "12345"
                ]
              ]
 } ?

c)

{
   _id: "joe",
   name: "Joe Bookreader",
   addresses: [
                [
                  street: "123 Fake Street",
                  city: "Faketon",
                  state: "MA",
                  zip: "12345"
                ],
                {
                  street: "1 Some Other Street",
                  city: "Boston",
                  state: "MA",
                  zip: "12345"
                }
              ]
 } ?

d) None of the mentioned
View Answer

Answer: a
Explanation: In this one-to-many relationship between patron and address data, the patron has multiple address entities.

7. How will avoid mutable, growing arrays in the following schema?

{
   name: "O'Reilly Media",
   founded: 1980,
   location: "CA",
   books: [12346789, 234567890, ...]
}

{
    _id: 123456789,
    title: "MongoDB: The Definitive Guide",
    author: [ "Kristina Chodorow", "Mike Dirolf" ],
    published_date: ISODate("2010-09-24"),
    pages: 216,
    language: "English"
}

{
   _id: 234567890,
   title: "50 Tips and Tricks for MongoDB Developer",
   author: "Kristina Chodorow",
   published_date: ISODate("2011-05-06"),
   pages: 68,
   language: "English"
} 

a)

{
   _id: "oreilly",
   name: "O'Reilly Media",
   founded: 1980,
   location: "CA"
}

[
   _id: 123456789,
   title: "MongoDB: The Definitive Guide",
   author: [ "Kristina Chodorow", "Mike Dirolf" ],
   published_date: ISODate("2010-09-24"),
   pages: 216,
   language: "English",
   publisher_id: "oreilly"
]

{
   _id: 234567890,
   title: "50 Tips and Tricks for MongoDB Developer",
   author: "Kristina Chodorow",
   published_date: ISODate("2011-05-06"),
   pages: 68,
   language: "English",
   publisher_id: "oreilly"
}

b)

{
   _id: "oreilly",
   name: "O'Reilly Media",
   founded: 1980,
   location: "CA"
}

[
   _id: 123456789,
   title: "MongoDB: The Definitive Guide",
   author: [ "Kristina Chodorow", "Mike Dirolf" ],
   published_date: ISODate("2010-09-24"),
   pages: 216,
   language: "English",
   publisher_id: "oreilly"
]

[
   _id: 234567890,
   title: "50 Tips and Tricks for MongoDB Developer",
   author: "Kristina Chodorow",
   published_date: ISODate("2011-05-06"),
   pages: 68,
   language: "English",
   publisher_id: "oreilly"
]

c)

{
   _id: "oreilly",
   name: "O'Reilly Media",
   founded: 1980,
   location: "CA"
}

{
   _id: 123456789,
   title: "MongoDB: The Definitive Guide",
   author: [ "Kristina Chodorow", "Mike Dirolf" ],
   published_date: ISODate("2010-09-24"),
   pages: 216,
   language: "English",
   publisher_id: "oreilly"
}

{
   _id: 234567890,
   title: "50 Tips and Tricks for MongoDB Developer",
   author: "Kristina Chodorow",
   published_date: ISODate("2011-05-06"),
   pages: 68,
   language: "English",
   publisher_id: "oreilly"
}

d) None of the mentioned
View Answer

Answer: c
Explanation: To avoid mutable, growing arrays, store the publisher reference inside the book document.

8. __________ define what records to select for read, update, and delete operations.
a) Query optimizer
b) Query selector
c) Update definitions
d) All of the mentioned
View Answer

Answer: b
Explanation: Update definitions, which define what fields to modify during an update.

9. The ___________ JavaScript shell and the MongoDB language drivers translate between BSON and the language-specific document representation.
a) mongod
b) mongo
c) json
d) none of the mentioned
View Answer

Answer: b
Explanation: MongoDB stores documents on disk in the BSON serialization format. BSON is a binary representation of JSON documents, though it contains more data types than JSON.

10. Which of the following statement is incorrect about documents in MongoDB?
a) The field names cannot start with the dollar sign ($) character
b) The field names cannot contain the dot (.) character
c) The field names cannot contain the null character
d) None of the mentioned
View Answer

Answer: d
Explanation: BSON documents may have more than one field with the same name.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter