That "works" for about as long as you have <10 employees and <3 customers or so. After that the railsapp doesn't get to be the sole owner of the db.
Jeff Bezos famously said[1] that anyone who does otherwise should be fired, and I agree.
But this is only valid when you're trying to build AWS. Not everyone does that.
Relational databases have extensive permission systems for a reason.
Yeah, and databases expose extensive APIs with extremely battle-tested security and permissions models for multiple consumers.
How do you keep that all in sync across your apps?
By “don’t do it,” I mean having multiple apps talk to one DB schema.
Services are slow, restrictive, and don't enjoy the benefits of an actual DBMS, like transactions. You also add additional dependencies and failure points.
All you've done is shifted the dependency and made extra work when schemas change. Now we have schema updates, _and_ service updates.
As I said, you give up transactions, performance, and flexibility. You also increase the workload, and increase failures. There is almost no good reason for what you're proposing.
1. DB -> App = Two updates, the schema and the app
2. DB -> Service -> App = Three updates, the schema, the service, and the app
In both cases, obviously the DB changes.
In both cases, obviously the App changes.
In the second case, you also get to update your services.
The same is true for API contracts but the culture of changing an API is much more understood as something that must be communicated and processes are more rehearsed.
Literally everything you just said applies to services and API contracts as well. You haven't solved anything.
> the culture of changing an API is much more understood as something that must be communicated and processes are more rehearsed
You're just making this up. There are thousands of incidents every day because someone changed an API without communicating to every stakeholder.
"Services are better than databases because service owners are better at communicating changes than database owners" isn't a very compelling argument.
I'd work to fix the communication problem before I adopted a terrible tech solution.
> You're just making this up. There are thousands of incidents every day because someone changed an API without communicating to every stakeholder.
What you wrote isn't a contradiction of what I wrote. I wrote "more understood" not "perfectly solved problem."
> "Services are better than databases because service owners are better at communicating changes than database owners" isn't a very compelling argument.
Except they are because the tooling is better. I can check calls to an API endpoint using the same tooling that I would for checking end user API calls. I can push out comms to use the new API, I can confirm calls go to 0 before deleting the old endpoint.
For checking that a table or column is being accessed before changing / deleting it? Fuck, I don't actually know how I'd orchestrate that. And once I've made that change (vs when I make an API change), well, I hope I got it 100% correct because reverting that change is harder.
Of course in a narrow case where all apps that need the same DB need to be upgraded/fixed in lockstep, maybe you can get away by directly updating the database. But more than 2 teams, it will quickly be a nightmare of conflicting priorities across teams, amount deployment coordination required.
"Oh you cannot change this schema right now because 3 other apps depend on it and they dont have time to make the necessary changes in their app to accommodate this right now, for the next 6 months"
When your apps connect to a DB schema, the change is silent. You just run ALTER TABLE and… whoops, you just brought down a service you didn’t know existed because the contract was implicit.