How would you use the cache-aside pattern for a read-heavy API endpoint?

Use cache-aside for a read-heavy API endpoint

Explains the cache-aside pattern for read-heavy endpoints and how misses, TTLs, and source-of-truth reads fit together.

1Say itAnswer out loud first

2CompareCompare with Core answer

3RefineRefine with Stronger and Advanced

TL;DR

With cache-aside, the API first tries to read a value from Redis by key. If the value is present, it returns it. If the value is missing, the API reads from the database or source service, stores the result in Redis with a TTL, then returns it. The database remains the source of truth, and Redis is a performance layer.

Full answer below

Practice focus

Cache miss flow, source-of-truth reads, TTLs, key choice, stale data, and fallback behavior.

Answer first

Answer path

Core answer first, then checkpoints toward a stronger answer.

Start
Core answer
Start here. This is the direct spoken answer to practice first.
Why this question matters
Cache-aside keeps the source system authoritative while the application owns lookup, miss loading, storage, and expiration. The exact miss and refresh path determines whether the cache reduces load or merely moves complexity into request handling.
With cache-aside, the API first tries to read a value from Redis by key. If the value is present, it returns it. If the value is missing, the API reads from the database or source service, stores the result in Redis with a TTL, then returns it. The database remains the source of truth, and Redis is a performance layer.
Checkpoint
Stronger answer
Optional upgrade with examples, trade-offs, and sharper phrasing.
I would choose the key and TTL from the business behavior. For a product catalog, a key might include product id, language, currency, tenant, and response version. On a cache miss, I would load only the needed shape, cache the serialized response or read model, and set an expiration that matches acceptable freshness. I would avoid caching errors, permissions-sensitive data without scope, or huge responses that create memory pressure.

Review signals

Use these to catch weak phrasing, shallow reasoning, and risky claims.

Common mistakesCandidateCommon mistakesMistakes that weaken the answer or signal shallow understanding.Open details

Details

Caching every endpoint without proving it is read-heavy.
Using keys that omit tenant, locale, permissions, or response version.
Caching database entities directly when the API shape is what is reused.
Ignoring the cache miss path under load.

How would you use the cache-aside pattern for a read-heavy API endpoint?

Practice focus

Answer path

Why this question matters

Review signals

Follow-up prompts

Continue the section

Tech stacks

Skill areas

Suggest an improvement