What ways of scaling databases do you know?

Main methods of database scaling:

1. Vertical Scaling (Scale Up) — increasing resources of a single server (CPU, RAM, disk). A simple method but limited by hardware capabilities.

2. Horizontal Scaling (Scale Out) — adding new servers to the cluster.

   • Sharding — dividing data across different servers based on a key to distribute load.
   • Replication — copying data from the primary server to replicas to improve availability and distribute read load.

3. Caching — using external caches (e.g., Redis, Memcached) to reduce database load.

4. Using specialized databases — for example, NoSQL for certain types of loads where scaling is easier.

The choice of method depends on requirements for availability, speed, and data volume.