alt Hacker NewsTill the financial controller shows up at the very least.
Also even if not required makes reasoning about how systems work a hell lot easier. So for vast majority that doesn't need massive throughtputs sacrificing some speed for easier to understand consistency model is worthy tradeoff
All financial systems don't care about time.
Prety much all financial transactions are settled with a given date, not instantly. Go sell some stocks, it takes 2 days to actually settle. (May be hidden by your provider, but that how it works).
For that matter, the ultimate in BASE for financial transactions is the humble check.
That is a great example of "money out" that will only be settled at some time in the future.
There is a reason there is this notion of a "business day" and re-processing transactions that arrived out of order.