I think what they’re proposing is something like “if I want to read and then update a value, incrementing it by one, the proper way to do that is to tell the DB to increment whatever value it has stored; not to increment my local representation of the value and then tell the DB to overwrite the value with it.”
The number of times I've had to increment a value by one are minimal. Or similar things where you want to update one value based on the other values, and do it in an atomic way.
But if I had to increment specifically, and were using ActiveRecord... I'd use the ActiveRecord increment! method. Which has the proper db-atomicity semantics you want, it does execute `UPDATE x SET n = n+1 WHERE pk = y ...`
This is not obvious unless you think about it - I've seen issues like this because the code looks correct if you ignore the update semantics, especially when it wont fail on your local dev env because in memory state will be the same as DB state since you're the only one hitting it...
Having to think about these things because the abstraction is leaky instead of just using the SQL where the transformation is explicit is not worth the hassle.
Using Clojure and yesql was a real pleasure for this - Clojure is immutable so you're working with values all over the place - and working with SQL query is just passing values in it and getting values out - no magic mapping - it's just values - if you want the latest value - query again, if you want to store a new value - send the new value. No mutation, no magic, just data.
