Caching is a fundamental performance optimization technique that stores copies of frequently accessed data in fast-access storage layers, reducing latency from milliseconds to microseconds and dramatically decreasing load on backend systems. Effective caching sits at the intersection of data locality, consistency models, and eviction policies — choosing the wrong strategy can create data staleness issues or cache stampedes that bring down entire systems. In 2026, caching is no longer an optional optimization: microservices amplify latency costs, cloud spend scales with repeated computation, and AI/LLM workloads have introduced entirely new caching dimensions — from semantic similarity matching to GPU-resident KV attention caches. The key insight: caching is about intelligently deciding what to cache, when to invalidate it, how to handle failures, and increasingly, how to apply it to non-deterministic AI inference pipelines.
What This Cheat Sheet Covers
This topic spans 21 focused tables and 149 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.
Table 1: Core Caching Patterns
| Pattern | Example | Description |
|---|---|---|
data = cache.get(key) if data is None: data = db.query(key) cache.set(key, data, ttl=3600) | • Application checks cache first on read • on miss, fetches from DB and populates cache • most common pattern providing explicit application control. | |
data = cache.get(key) | • Cache automatically loads from DB on miss using registered loader • abstracts cache logic from application code. | |
cache.set(key, data)db.write(key, data) | • Writes update both cache and DB synchronously • ensures strong consistency but adds write latency. | |
cache.set(key, data)queue.push(db_write_task) | • Writes update cache immediately and DB asynchronously after delay • optimizes write performance with eventual consistency. | |
db.write(key, data)cache.delete(key) | • Writes bypass the cache entirely • prevents cache pollution from write-once data but causes read misses after writes. |