tional groups across databases. Splitting data within functional areas across multiple databases, or sharding, ¹ adds the second dimension to horizontal scaling. The diagram in figure 1 illustrates horizontal data-scaling strategies.

As figure 1 illustrates, both approaches to horizontal scaling can be applied at once. Users, products, and transactions can be in separate databases. Additionally, each functional area can be split across multiple databases for transactional capacity. As shown in the diagram, functional areas can be scaled independently of one another.

FUNCTIONAL PARTITIONING

Functional partitioning is important for achieving high degrees of scalability. Any good database architecture will decompose the schema into tables grouped by functionality. Users, products, transactions, and communication are examples of functional areas. Leveraging database concepts such as foreign keys is a common approach for maintaining consistency across these functional areas.

Relying on database constraints to ensure consistency across functional groups creates a coupling of the schema

AN

AC ID ALTERNATIVE