There are two parts to this. You are correct that RDS doesn't help you with picking the index strategy, or optimizing queries. I don't see that as running the DB though, that is how you interact with it once its running. What it does do it help you reliably run the DB server itself.
Without any effort you can stand up a redundant, high availability deployment. With all of the data encrypted at rest. And configure nightly backups, which are stored on redundant storage in multiple physical locations and also encrypted. You can then restore those backups into a working system with the click of a button. Oh, and minor version patches happen automatically with no downtime. And you can click a button to do major version updates.
The last time I did analysis on it, which was a while ago, all of those features cost us less than 8 hours of my time each year. It would probably take more than 8 hours of my time each year just to handle security patches on the systems. Let alone the amount of engineering that it would take to get a system as redundant and reliable as a DB in RDS. I will happily pay them to take all of that off my plate so I can focus on other things, like optimizing the queries.
> Without any effort you can stand up a redundant, high availability deployment.
Yes, it is seductive. Sometimes worth it.
But realize you'll be paying monthly in perpetuity for the convenience of that one-time setup which could've been done a a few days, give or take.
> all of those features cost us less than 8 hours of my time each year
I'm surprised! Our RDS costs are about 10 engineering hours per month (120 eng/hrs per year). This is with hardly any customer traffic or data yet (early startup phase).
It's worth it for now, but it'll become unreasonably expensive later.
I should clarify that the 8 hours was above and beyond the costs of running it yourself on AWS. So that is not counting the 2x ec2 instances, plus the minor s3 and elb costs. Didn't really run the numbers for equivalent hardware elsewhere, since that wasn't an option for us. Eyeballing it real quick right now, its still maybe an hour / month vs other places for the hardware. It is a relatively small instance though, saving probably are much better as it gets to larger sizes. Pre-paying for reserved instances helps here as well.
Without any effort you can stand up a redundant, high availability deployment. With all of the data encrypted at rest. And configure nightly backups, which are stored on redundant storage in multiple physical locations and also encrypted. You can then restore those backups into a working system with the click of a button. Oh, and minor version patches happen automatically with no downtime. And you can click a button to do major version updates.
The last time I did analysis on it, which was a while ago, all of those features cost us less than 8 hours of my time each year. It would probably take more than 8 hours of my time each year just to handle security patches on the systems. Let alone the amount of engineering that it would take to get a system as redundant and reliable as a DB in RDS. I will happily pay them to take all of that off my plate so I can focus on other things, like optimizing the queries.