Comment by randunel

I don't see the difference between a ledger (possibly with a unique sequence enforcement) which would take the balance to a negative number, and a mutable row in a relational database with optimistic locking (same unique sequence enforcing). Would you mind helping me out, how would a ledger work better to prevent a negative balance, given that the enforcement isn't specific to ledgers and can be used in relational DBs? After all, both can go to negative balance by applying atomic subtractions, and both can prevent writes with the wrong sequence.