All 7 Caching Patterns questions
More in Caching Patterns
What is the cache aside pattern, and how does it work with Redis? What is the write behind, also called write back, caching pattern, and what risk does it introduce? How does the read through caching pattern work, and how is it different from cache aside from the application's perspective? How do you decide which caching pattern, cache aside, write through, or write behind, is right for a specific application feature? How would you prevent a cache stampede, where many requests simultaneously try to regenerate the same expired cache entry at once? How do you implement cache invalidation correctly when the same underlying data is cached under multiple different keys?
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Redis › Caching Patterns

What is the write through caching pattern, and how does it differ from cache aside?

Beginner

Answer

In the write through pattern, every time data is written to the database, it is also immediately written to Redis at the same time, keeping the cache always up to date, unlike cache aside where Redis is only populated when data is actually read and requested.
def update_user(user_id, data):
    database.update_user(user_id, data)
    redis.set(f'user:{user_id}', data)
Real-world example An inventory system updates both the database and Redis together whenever stock levels change, ensuring the cached inventory count is always accurate and never stale.

Common follow-ups: What is the tradeoff of writing to both the database and cache on every update?;Does write through caching increase the time a write operation takes?

Caching Patterns;Redis Memory Optimization
All 7 Caching Patterns questions