MongoDB MongoDB Data Modeling 1 — Questions and Answers
Question 1: What is the embedded document (denormalized) data model in MongoDB?
- Storing related data as separate referenced documents
- Storing related data as nested subdocuments within a single document (Correct answer)
- Embedding JavaScript functions in documents
- Using base64 encoding for binary data
Correct answer: Storing related data as nested subdocuments within a single document
Embedding stores related data in a single document as nested subdocuments, improving read performance by avoiding joins but potentially increasing document size.
Question 2: When should you prefer the reference (normalized) data model over embedding?
- When documents are always queried together
- When data is rarely accessed
- When data is frequently accessed independently or shared across multiple documents (Correct answer)
- When documents are small and simple
Correct answer: When data is frequently accessed independently or shared across multiple documents
References (storing related document _ids) are preferred when related data is large, changes frequently, or is shared by multiple parent documents.
Question 3: What is MongoDB's document size limit?
- 1 MB
- 4 MB
- 16 MB (Correct answer)
- 64 MB
Correct answer: 16 MB
MongoDB limits individual documents to 16 MB, which prevents excessive memory usage and encourages proper data modeling.
Question 4: What is the 'bucket pattern' in MongoDB data modeling?
- Distributing documents across multiple collections
- Grouping time-series data into documents covering a time range (Correct answer)
- Storing binary data in chunks
- Creating separate collections per user
Correct answer: Grouping time-series data into documents covering a time range
The bucket pattern groups related time-series data into documents that each cover a defined time period, reducing the number of documents and improving query performance.
Question 5: What is the 'outlier pattern' in MongoDB data modeling used for?
- Handling documents with unusually large field counts
- Handling documents whose arrays would exceed the size limit by using overflow documents (Correct answer)
- Filtering statistical outliers in queries
- Handling rare edge cases in schema validation
Correct answer: Handling documents whose arrays would exceed the size limit by using overflow documents
The outlier pattern handles edge cases where most documents have small arrays but a few have very large ones by storing overflow data in additional linked documents.
Question 6: Which of the following best describes a polymorphic schema in MongoDB?
- A schema that changes automatically over time
- A collection storing documents with varying but related structures (Correct answer)
- A schema generated from multiple programming languages
- A schema that inherits from a parent schema
Correct answer: A collection storing documents with varying but related structures
Polymorphic schema allows different documents in the same collection to have different fields while still representing related entities.
MongoDB MongoDB Data Modeling 1
What is the embedded document (denormalized) data model in MongoDB?