Professional Azure SQL Database Administration

Horizontal Scaling

Horizontal scaling or sharding refers to partitioning the data from one single big table in a database, across multiple independent databases based on a sharding or partitioning key. For example, a customer table is partitioned across multiple independent databases on CustomerID. Each independent database stores data for one or more customers.

Horizontal scaling can be helpful when:

• The data is too big to fit in one single database.
• The data is to be distributed to different locations for improved performance or for compliance. For example, European customers will get improved performance if their data is in a European data center rather than an Asian data center.
• Isolating tenants or customers to a database of their own for ...