[charcircuit]

Isn't that true for almost all software? You only need to know the implementation of a small subset of parts. I would say databases are worse since you need to know how they are implemented else you will start making O(rows) queries or doing other inefficient stuff.

[jrm4]

Going broadly (which is all I can do because I teach this stuff and don't build in depth) -- "the database" is the part I can most easily "abstract" away as if it were walled off?

As opposed to aspirationally discrete classifications that end up being porous, e.g. MVC, "Object Oriented" etc.