Cookie-based sessions vs database sessions in Django - Visual Side-by-Side Comparison

Concept Flow - Cookie-based sessions vs database sessions

User makes request

↓

Check session type

↓

Cookie-based

↩repeats flow] repeats flow]

This flow shows how a web request checks the session type, reads session data either from a cookie or database, uses it, and sends a response with updated session info.

Execution Sample

Django

def get_session_data(request):
    if SESSION_ENGINE == 'cookie':
        return request.COOKIES.get('session')
    else:
        return db.get_session(request.session_key)

This code chooses how to get session data based on session engine setting.

Execution Table

Step	Session Type	Action	Session Data Source	Session Data Retrieved	Response Action
1	Cookie-based	Check cookie for session	Cookie	Session data from cookie string	Send response with updated cookie
2	Cookie-based	Use session data in app	Cookie	Session data from cookie string	Send response with updated cookie
3	Database-based	Check session key in request	Database	Session data from database record	Send response with updated session ID cookie
4	Database-based	Use session data in app	Database	Session data from database record	Send response with updated session ID cookie
5	Exit	No more requests	-	-	-

💡 Execution stops when no more requests are made.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
SESSION_ENGINE	'cookie'	'cookie'	'cookie'	'database'	'database'	'database'
request.COOKIES['session']	None	'session_data_cookie'	'session_data_cookie'	None	None	None
request.session_key	None	None	None	'abc123'	'abc123'	'abc123'
session_data	None	'session_data_cookie'	'session_data_cookie'	None	'session_data_db'	'session_data_db'

Key Moments - 2 Insights

Why does cookie-based session store all data in the cookie, but database-based only store a session ID?

Cookie-based sessions keep all session data inside the cookie sent to the browser (see Step 1), so the server reads it directly. Database sessions store only a session ID in the cookie (Step 3), and the full data is fetched from the database using that ID.

What happens if the cookie is too large in cookie-based sessions?

Cookies have size limits (usually around 4KB). If session data is too big, cookie-based sessions can fail or truncate data. Database sessions avoid this by storing data server-side (Step 3 and 4).

Visual Quiz - 3 Questions

Look at the execution table, at which step does the app read session data from the database?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Check the 'Session Data Source' column for 'Database' in the execution table.

According to the variable tracker, what is the value of SESSION_ENGINE after Step 4?

A 'database'

B None

C 'cookie'

D 'file'

💡 Hint

Look at the SESSION_ENGINE row under 'After Step 4' in the variable tracker.

If the SESSION_ENGINE is set to 'cookie', what will be the source of session data at Step 2?

A Database

B Cookie

C File system

D Environment variable

💡 Hint

Refer to the 'Session Data Source' column for Step 2 in the execution table.

Concept Snapshot

Cookie-based sessions store all session data inside the browser cookie.
Database sessions store only a session ID in the cookie and keep data on the server.
Cookie sessions reduce server load but have size limits.
Database sessions handle larger data securely but require database access.
Django settings control which session engine is used.
Choose based on app needs and security considerations.

Full Transcript

This visual execution compares cookie-based and database-based sessions in Django. When a user makes a request, the app checks the session engine setting. For cookie-based sessions, it reads all session data directly from the cookie sent by the browser. For database sessions, it reads a session ID from the cookie and fetches full session data from the database. The app then uses this session data and sends a response with updated session info. Cookie sessions keep data client-side, which can be faster but limited in size. Database sessions keep data server-side, allowing larger and more secure storage but require database queries. The execution table shows steps for both types, and the variable tracker follows key variables like SESSION_ENGINE and session data. Key moments clarify why data location differs and cookie size limits. The quiz tests understanding of when and where session data is read and stored. This helps beginners see how Django manages sessions differently based on configuration.