Amazon Web Services' relational database service, Amazon RDS, is a MySQL database hosted in the cloud with limitations such as connection limits and an inflexible pricing structure. In contrast, PlanetScale is a MySQL database also hosted in the cloud but designed to scale with growth and fit into developer workflows. The main reasons businesses are switching from RDS to PlanetScale are scalability issues with connection limits and connection pooling, as well as the total cost of ownership and the complexity of using RDS. PlanetScale's technology allows for non-blocking schema changes, staging branches, and CI/CD workflow automation, making it easier for developers to manage databases without downtime or maintenance windows. Additionally, PlanetScale offers a better developer workflow that reduces time to feature and overhead associated with data tickets.