Can you explain how database sharding works?

Sharding is a method of horizontally partitioning a database into multiple parts (shards), each of which stores a subset of the data. This allows distributing the load and increasing scalability.

Working mechanism:

• Data is divided based on a certain criterion (for example, by key range or hash of the key).
• Each shard is a separate database or server responsible for its part of the data.
• When a request is made, the system determines which shard to direct the request to, based on the key.

Example: if you have a user table, you can shard by user ID: users with IDs 1-10000 in the first shard, 10001-20000 in the second, and so on.

This reduces the load on a single server and increases fault tolerance, but requires additional routing logic for requests and can complicate transactions between shards.