Can you explain the concept of sharding and how it is applied in databases?

Sharding is a method of horizontal scaling of a database, where data is divided into parts (shards), each stored on a separate server or node. This allows distributing the load and increasing the system's performance and availability.

In a database, sharding is applied as follows:

• Data is divided based on a key (for example, by user ID or geographic attribute).
• Each shard contains only a part of the data related to a specific range of keys.
• Requests are directed to the appropriate shard node, reducing the load on each individual server.

For example, if you have a user database, you can shard it by the first letter of the last name: users with last names starting with A–F go to one shard, G–L to another, and so on. This allows processing requests in parallel and scaling the system as data grows.