Database query optimization in Flask - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is database query optimization in Flask applications?

It is the process of making database queries faster and more efficient to improve app performance and reduce server load.

beginner

Why should you avoid querying the database inside a loop in Flask?

Because it causes many separate queries, slowing down the app. Instead, fetch all needed data in one query.

intermediate

What is eager loading in Flask SQLAlchemy?

Eager loading fetches related data in the same query to avoid extra database hits later, speeding up data access.

intermediate

How does indexing help optimize database queries?

Indexes let the database find data faster, like a book's index helps find pages quickly, reducing query time.

beginner

What is the benefit of using Flask's query filters instead of filtering in Python?

Filtering in the database reduces data sent to the app, making queries faster and saving memory.

Which method reduces the number of database queries by loading related data together in Flask SQLAlchemy?

A Eager loading

B Lazy loading

C Filtering in Python

D Using raw SQL

Eager loading fetches related data in one query, reducing multiple database hits.

What is a common cause of slow database queries in Flask apps?

A Using indexes

B Querying inside loops

C Caching results

D Using query filters

Querying inside loops causes many queries, slowing down the app.

How do indexes improve query speed?

A By compressing data

B By sorting data alphabetically

C By creating a fast lookup structure

D By caching queries

Indexes create a structure that helps the database find data quickly.

Why is filtering data in the database better than filtering in Python?

A It reduces data transfer and speeds up queries

B It makes Python code simpler

C It uses more memory

D It slows down the app

Filtering in the database sends less data to the app, improving speed.

Which Flask extension is commonly used for database ORM and query optimization?

A Flask-Mail

B Flask-Login

C Flask-WTF

D Flask-SQLAlchemy

Flask-SQLAlchemy provides ORM features and tools for query optimization.

Explain how you would optimize database queries in a Flask app to improve performance.

Think about reducing the number of queries and data size.

Describe the role of indexing and eager loading in database query optimization.

Compare to how a book index helps find pages quickly.