[smoyer]

"But that's not going to be database agnostic!"

Haha ... I'll admit I used to say that but rarely did an internal system (what I work on most) ever actually have that requirement. Systems that are sold to customers to run on their premises are another story but don't worry about using PostgreSQL-only (e.g.) features to speed up both your processing and development times. I have however seen the horrors of 600 line stored-procedures with calls to other stored-procedures nested 15 deep. If you get to the point that you can't easily understand the business logic, you've gone too far.

[mumblemumble]

There seem to be two ways that interacting with the database works out in practice: You can embrace the specific DBMS you have, get the most out of it, and end up tightly coupled to it. Or you can try to be database agnostic, increase your development costs and limit your performance and data expressivity in the service of that goal, and still end up tightly coupled to the DBMS.

My pet hypothesis is that "database agnostic" isn't really about being able to switch databases on a whim. It's more expressing a developer-centric anxiety. A dog whistle way of saying, "I don't want to have to RTFM of a new DBMS." Which I get, most DBMSes have awful manuals. Especially SQL databases. SQL dialects tend to mix syntax, semantics, and subtle implementation details all together into one big ball of mud and tangled hair. But this is one spot where I think it really is worthwhile to hold your nose and get through it.