How can the performance and data volume in an SQL database be increased through scaling?

Two main approaches are used to increase performance and data volume in an SQL database through scaling:

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

2. Horizontal Scaling (Scale-Out) — distributing data and load across multiple servers.

   • Sharding — dividing the database into parts (shards) by key, each stored on a separate server. This increases data volume and query parallelism.

   • Replication — copying data to multiple servers to improve availability and distribute read load.

Example of sharding:

-- Suppose we have a users table, and we shard by region
-- Queries for users from region A go to shard_A server
-- Queries for users from region B go to shard_B server

Thus, scaling allows handling more data and queries but requires a well-thought-out architecture and management.