When should you shard your database?

Databases should be sharded only when all other database optimization strategies (such as caching, upgrading to larger servers) fail to improve performance. This is because sharding databases increase the operational complexity of performing operations on the database. One such situation could be the exceeding limit of a single database node implemented on your application when it is used by an immense number of users.

Before we move on, let's revise a little about databases.