Redis

Definition: Redis is a fast, in-memory NoSQL data store that stores data primarily in RAM using key-value structures; it can be used as a database, cache, message broker, and more.
Because data is kept in memory, Redis can provide very low-latency access, while it also supports persistence to disk when needed.

3 good examples

1. Caching

   User → API → Redis → Product information
                   ↓
                PostgreSQL
   

   Frequently requested products can be kept in Redis so the application doesn’t query PostgreSQL every time.

2. Session storage

   session:abc123 → {
       userId: 42,
       role: "customer"
   }
   

   Redis can store login/session information with an expiration time (TTL).

3. Rate limiting

   user:42:requests → 57
   

   You can count how many API requests a user has made and reject requests after, for example, 100 requests per minute. Redis’s atomic operations and expiration make this pattern useful.

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Database My-Journey-In-Codeless