Comment by krackers

Double-entry: each row of your DB stores {debit account, credit account, amount}.

Single-entry: each row of your DB stores {account, delta}.

With double-entry you are guaranteed via your schema that sum(debit delta) = sum(credit delta), that's it. Money is "conserved".

It's easy to denormalize the double-entry into a single-entry view.

That kleppman article talking about movements as edges of a DAG is the only place this is ever talked about clearly.