Does RDS for MySQL Support Multiple Accounts?
Yes, RDS for MySQL supports multiple accounts. You can assign different rights to these accounts through authorization commands to control access to different tables. Each table can be controlled independently.
Performance is not affected when multiple accounts access tables. Concurrent access of multiple sessions increases system resource overhead. For details, see the number of connections in Relational Database Service Performance White Paper.
For more details about MySQL permissions, see official MySQL documents.