Promoting an RDS read replica to master

We're going to show you how to promote an RDS read replica to be a primary instance. There are a few reasons you might like to do this:

• To handle a table migration that would typically cause a large amount of downtime, especially when messing with columns or indexes
• Because you need to implement sharding
• Recovery from failure, should you choose not to deploy your existing primary in multi-AZ mode (not recommended)

Getting ready

You're going to need the unique ID that has been assigned to an RDS read replica. If you followed the Creating a database with automatic failover and Creating a database read replica recipes, then you'll be all set.

It's also a good idea...