Key-value stores are the simplest NoSQL pattern:
GET user:123 → {"name": "John", "email": "j@x.com"}
SET session:abc → {"user_id": 123, "expires": ...}
Characteristics:
- O() lookups by key
- No query language (just GET/SET)
- Values are opaque blobs
- Extremely fast and scalable
Use cases:
- Session storage
- Caching layer
- Shopping carts
- User preferences
Examples: Redis, Memcached, Amazon DynamoDB (also document)
Perfect when you always know the key. Limited when you need to query by value.