What is the difference between replication and sharding?

Replication and sharding are two different approaches to scaling and increasing database fault tolerance.

Replication is the process of copying data from one server (master) to one or more servers (replicas). The goal is to increase availability and provide backup. In replication, all replicas contain the same data, and reads can be performed from any replica, while writes usually go to the master.

Sharding is the horizontal partitioning of data into parts (shards), each stored on a separate server. The goal is to distribute load and increase the volume of stored data. Each shard contains a unique part of the data, and requests are directed to the appropriate shard.

Example:

• Replication: one database with customer data is copied to multiple servers for fault tolerance.
• Sharding: the customer database is divided by regions, and data for each region is stored on a separate server.