As the saying goes (I forget who originally said it):
“The database is not the truth: it’s a cache of a subset of the truth.”
It’s very valid to use a classic SQL database sparingly in a BEAM application, using it only for persisting in case of emergency reload of “start state”, because we have so many more choices between “no database” and “the database is everything” to work with.
Lots of other languages lack the abstractions for creating data store layers that can work both as the primary source of truth and also persist things to other sources, but they’re so cheap in terms of developer time because of OTP that it’s almost wasteful not to use them and treat everything as if it’s Ruby.
I guess what I want to say, in short, is the question should probably be “Do you really need to read/write to the database all the time, or can you just use it as a bucket where you pull starting state from?”.
