Anti-patterns to avoid in MongoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the 'One Big Collection' anti-pattern in MongoDB?

It is when all data is stored in a single collection without proper structure, causing slow queries and difficulty in managing data.

beginner

Why should you avoid embedding large arrays inside documents in MongoDB?

Because large arrays can cause document size to grow too big, leading to performance issues and hitting MongoDB's document size limit.

beginner

What problem arises from using unindexed queries frequently in MongoDB?

Unindexed queries cause full collection scans, which slow down performance and increase resource usage.

intermediate

Explain the 'Overusing Joins' anti-pattern in MongoDB.

MongoDB is not designed for heavy join operations; overusing $lookup or manual joins can degrade performance and complicate queries.

intermediate

Why is ignoring schema design considered an anti-pattern in MongoDB?

Ignoring schema design leads to inconsistent data, harder maintenance, and inefficient queries, even though MongoDB is schema-flexible.

Which of the following is a common MongoDB anti-pattern?

A Using indexes on frequently queried fields

B Embedding small related documents

C Storing all data in one large collection

D Designing a clear schema

Storing all data in one large collection without structure is an anti-pattern that causes slow queries.

What happens if you frequently run queries without indexes in MongoDB?

A Full collection scans slow down performance

B Queries run faster

C Data gets deleted automatically

D Indexes are created automatically

Without indexes, MongoDB scans the entire collection, which slows down queries.

Why should large arrays inside documents be avoided in MongoDB?

A They improve query speed

B They can exceed document size limits and reduce performance

C They automatically create indexes

D They simplify schema design

Large arrays can make documents too big, hitting size limits and hurting performance.

What is a downside of overusing $lookup for joins in MongoDB?

A It can degrade performance and complicate queries

B It automatically indexes joined fields

C It reduces data duplication

D It speeds up queries

$lookup joins are costly and can slow down queries if overused.

Ignoring schema design in MongoDB can lead to:

A Automatic schema enforcement

B Easier maintenance

C Consistent and efficient data

D Inconsistent data and inefficient queries

Without schema design, data can become inconsistent and queries inefficient.

Describe three common anti-patterns to avoid when designing MongoDB databases.

Think about how data is stored, queried, and indexed.

Explain why ignoring schema design in MongoDB can cause problems, even though it is schema-flexible.

Consider the benefits of planning your data structure.