Custom cache keys in NestJS - Performance & Optimization

Performance: Custom cache keys

MEDIUM IMPACT

This affects how efficiently cached data is retrieved and reused, impacting response time and server load.

Caching API responses with unique keys for different query parameters

NestJS

const key = `userData:${userId}`;
cacheManager.set(key, data);

Generates unique keys per user, ensuring correct cached data is served without collisions.

📈 Performance Gainreduces cache misses and server load, improving response speed

Caching API responses with unique keys for different query parameters

NestJS

cacheManager.set('userData', data); // same key for all users

Using a single static cache key causes cache collisions and stale data for different users.

📉 Performance Costcauses frequent cache misses and redundant data fetching, increasing server response time

Performance Comparison

Pattern	Cache Hits	Cache Misses	Server Load	Verdict
Static key for all requests	Low	High	High	[X] Bad
Unique key per request parameters	High	Low	Low	[OK] Good

Rendering Pipeline

Custom cache keys optimize the server response phase by reducing redundant data fetching and processing.

→Server Processing

→Network Response

⚠️ BottleneckCache lookup efficiency and data retrieval

Core Web Vital Affected

INP

This affects how efficiently cached data is retrieved and reused, impacting response time and server load.

Optimization Tips

1Use unique cache keys that reflect request parameters to avoid collisions.

2Avoid static keys for dynamic data to prevent stale cache issues.

3Test cache effectiveness by measuring response times for repeated requests.

Performance Quiz - 3 Questions

Why is using a static cache key for all requests bad for performance?

A It causes cache collisions and stale data, increasing server load.

B It reduces server load by sharing cached data.

C It improves cache hit rate for all users.

D It decreases network latency automatically.

DevTools: Network

How to check: Open DevTools Network panel, observe response times for repeated requests with different parameters.

What to look for: Faster responses and fewer full data fetches indicate effective caching with custom keys.