# Cache-Aside Pattern — Redis

Source: https://www.geekswithgeeks.com/en/redis/redis-cache-aside

> Put Redis in front of a slower database to absorb repeat reads.

## Check cache, then the DB

The app checks Redis first. On a **hit**, it returns instantly. On a **miss**, it queries the real database, then writes the result into Redis for next time.

## The flow in commands

A miss followed by a warm cache for the next request.

```bash
GET product:501          # (nil) -> cache miss
# app queries the database for product 501 ...
SET product:501 "{...json...}" EX 300
GET product:501          # cache hit next time
```

## Always set a TTL

A cached entry without an expiry can quietly go stale forever. Even a generous TTL like an hour keeps data self-healing.