Step 1: Understand How Database Caching Works

Unlike Redis (which caches in RAM), Django's DatabaseCache creates a dedicated, highly indexed table in your primary SQL database (e.g., PostgreSQL, MySQL, or SQLite). Django serializes cached values and saves them as fast lookup rows, reducing heavy processing and rendering overhead.

Step 2: Define Your Backend in Settings

Open your settings.py and replace your existing dummy or local memory cache with the Database Cache backend. Provide a custom name for your cache table:

# settings.py
CACHES = {
    "default": {
        "BACKEND": "django.core.cache.backends.db.DatabaseCache",
        "LOCATION": "my_cache_table",
    }
}

Step 3: Run the Schema Migration Command

Because this backend stores its cache in an actual SQL table, you must tell Django to generate the schema. Run this command in your terminal:

python manage.py createcachetable

This creates my_cache_table with optimized indexes for expiration tracking and lightning-fast primary key lookups.

Step 4: Choose Your Caching Strategy

There are three main levels of caching in Django:

• Per-View Cache: Cache the entire HTTP response.
• Template Fragment Cache: Cache specific components of HTML.
• Low-level Cache API: Directly program what objects go in/out of the database.

Step 5: Cache Simple Static Views (e.g., About Page)

For static pages that read the same for every user, apply the @cache_page decorator directly inside your views file. Define your timeout in seconds (e.g., 7200 seconds for 2 hours):

from django.views.decorators.cache import cache_page
from django.shortcuts import render

@cache_page(7200)
def about_view(request):
    return render(request, 'about.html')

Step 6: Handle Dynamic Content (e.g., Lesson Page)

Avoid full-page caching if the page contains user-specific data (like user-customized navigation bars or learning progress). Instead, isolate the shared content (like the lesson text and video player) using Template Fragment caching.

Step 7: Implement Fragment Caching in Templates

Load the cache template library, wrap your block, specify a duration, assign an identifier name, and append dynamic cache keys (like lesson.id):

{% load cache %}

<!-- Dynamic: Welcome message is not cached -->
<h1>Welcome, {{ request.user.username }}</h1>

<!-- Static Lesson Fragment: Cached for 1 hour per unique lesson ID -->
{% cache 3600 lesson_content lesson.id %}
    <div class="video-container">
        {{ lesson.video_embed|safe }}
    </div>
{% endcache %}

Step 8: Write Cache Invalidation Signals

If you update a lesson or about page in the admin backend, users shouldn't have to wait for the cache timer to expire. Hook up a post_save or post_delete signal to clean up stale entries:

from django.db.models.signals import post_save
from django.dispatch import receiver
from django.core.cache import cache
from .models import Lesson

@receiver(post_save, sender=Lesson)
def invalidate_lesson_cache(sender, instance, **kwargs):
    # Construct the identical cache key used in templates and delete it
    cache.delete(f'template.cache.lesson_content.{instance.id}')

Step 9: Monitor Database Cache Size

Over time, expired cache records can accumulate and pollute your database storage. To clean up expired keys automatically, you can set up a crontab task or Celery beat task to clear out obsolete rows, or trust Django's automatic cleanup during key insertion.

Step 10: Know When to Upgrade to Redis

Database caching is wonderful because of its zero-infrastructure requirement. However, as traffic climbs, writing thousands of transient user-session cache rows back into your SQL server creates severe disk I/O bottlenecks. When you notice database performance dipping, swap DatabaseCache for RedisCache in your settings—your Django code and template tags will stay exactly the same!