Which AWS services should be used for read/write of constantly changing data?

To monitor and optimize turn on hyper-threading on your DB instance.

• You can use hyper-threading on your RDS for Oracle DB instances to optimize the licensing value of your software. Hyper-threading enables you to utilize an instance that has the required RAM for memory-intensive workloads but has fewer CPU cores.

Cloud SQL is the service which delivers fully handled relational databases in the cloud. It provides MySQL, PostgreSQL, and SQL Server database engines.

Advantages of using Amazon Relational Database Services:

• Managed service: Amazon RDS is a managed database service that helps businesses with hardware provisioning, software patching, and backups. This allows them to focus on their application.
• Scalability: Amazon RDS provides scalability to your database.
• Security: Amazon RDS uses encryption at rest and in transit, network isolation, and access control through AWS Identity and Access Management (IAM).
• Monitoring and metrics: Amazon RDS has metrics and monitoring options that help in monitoring the database.
• Compatibility: Amazon RDS supports a wide range of databases like MySQL, PostgreSQL, Oracle, SQL Server, and MariaDB.
• Integration with other AWS services: Amazon RDS offers Integration with other AWS services that helpyou to build and manage your application.

Amazon RDS is the best for running a MySQL database.