Storage engines, migrations and zero-downtime changes.
How do you architect a highly available, zero-downtime database migration in AWS RDS?
Zero downtime means you never ask for a maintenance window. Bring the new database up next to the old one, keep it in sync while the old one carries all the traffic, check the data constantly, then switch connections over in a few seconds, with a way back you set up before you need it.
Design a backup and recovery strategy for a production RDS database, including what point-in-time recovery can and can't actually do for you.
Automated backups and point-in-time recovery cover the everyday case, restoring to any second within the retention window, but every restore creates a brand-new instance rather than repairing the existing one, and neither protects against a whole-region outage on its own. Cross-region snapshot copies and manual snapshots fill the two gaps that leaves.
How do you safely rotate IAM credentials or database secrets without downtime?
The safe pattern is overlapping validity. Create the new secret while the old one still works, get code that accepts either one deployed everywhere, confirm the new one is actually being used, then revoke the old one. Rotating in a single step guarantees a window where something is still holding a credential that no longer works.