Caching Strategies#

Cache effectively to improve performance and reduce load.

Cache Layers#

Caching Patterns#

Cache-Aside (Lazy Loading)#

1. Check cache → miss
2. Query database
3. Store in cache
4. Return

Best for: Read-heavy, general purpose.

Write-Through#

1. Write to cache
2. Cache writes to DB (sync)
3. Return

Best for: Consistency critical, write-heavy.

Write-Behind#

1. Write to cache
2. Return immediately
3. Cache writes to DB (async)

Best for: High throughput writes, eventual consistency OK.

Refresh-Ahead#

• Cache proactively refreshes before expiry
• Reduces latency spikes on cache miss
• Requires predictive logic or scheduled refresh

Cache Invalidation#

Two hard things: naming, cache invalidation, off-by-one errors.

Redis Patterns#

• Use EXPIRE on every SET
• Use SCAN not KEYS in production
• Distributing: Redis Cluster for sharding
• Backup: RDB (snapshot) + AOF (append-only log)
• Monitor: hit rate, memory, evictions, latency