Design pattern to scale relational database horizontally

Database scalability is one of the critical factor in designing scalable web application. All the four major cloud vendors (Amazon, Microsoft, Google and Oracle) offers relational database as service which abstracts several complexities for developers to setup and manage database servers that helps developers focus on core application development.

Even though cloud vendors provides database as service, developers still need to design the application to scale database horizontally. Here are some design patterns to scale relational database horizontally:

1. Database Sharding

Divide your database into smaller, more manageable pieces called shards. Each shard contains a subset of the data and can be hosted on a separate server.

2. Read Replicas

Use read replicas to offload read traffic from the primary database. This is useful for read-heavy applications.

3. Caching

Implement caching at multiple layers - application level, database query level, and object level to reduce database load.

4. Connection Pooling

Use connection pooling to efficiently manage database connections and reduce overhead.