Which service provides a scalable relational database solution in the cloud?

Amazon RDS, or Amazon Relational Database Service, provides a scalable relational database solution in the cloud, making it highly suitable for applications that require traditional database features such as structured queries and relational data models. RDS supports various database engines like MySQL, PostgreSQL, Oracle, and SQL Server, allowing users to choose the database that best fits their application requirements.

One of the key features of Amazon RDS is its ability to automatically handle routine database tasks such as patching the database software, backing up databases, and enabling replication for enhanced availability. Additionally, RDS is designed to scale easily; you can modify the instance size or storage capacity with little to no downtime, ensuring that as your application grows, your database can adapt accordingly without manual intervention.

In contrast, other options such as Amazon DynamoDB are NoSQL databases designed for key-value and document data structures, which do not provide the traditional relational features of RDS. Amazon Glacier is primarily a low-cost cloud storage service for data archiving, not a database solution. Lastly, Amazon Redshift is a columnar data warehouse service optimized for analytics and reporting, which differs from the scalable relational database functionalities provided by RDS.