mickeyknoxnbk

He actually takes the situation of ATM's (which have a disconnected nature to your bank account and are a special case since they're often on dialup lines) and then tries to somehow leverage that to apply to all bank transactions. I work in finance and have for over 20 years. I assure you the bankend systems are not using NoSQL nor eventual consistency. A set of ATM transactions is sent to the backend via a "batch" and that whole batch is either applied or not applied in a transaction.

Edit: there is a discussion on this on HN which shows why his statements are misleading at best and wrong at worst

Does U.S. Cellular have enough money to build a time machine? Because I'd like to go back in time and visit El Bulli.

Pretty much any use case involving financial transactions. Do you want the money in your bank account to be eventually consistent?

How do former CIA members feel about the president trusting foreign sources and information over the information provided by the CIA?

It's a little more complicated than that. For example, it depends on the age and capabilities of the ATM itself. Some have full-time internet access, some are dialup, etc. The general protocol is available here:

https://en.wikipedia.org/wiki/ISO_8583

But you certainly could quickly visit multiple ATM's and withdraw money over your limit in some scenarios. The bank itself will put a limit on the per-ATM amount you can withdraw. They weigh that risk against your ability to quickly move between ATM's and the probability of you paying the overdraft fees. Meaning, you intentionally did this simply to get around the limits but you needed more cash. Or a thief did this in attempts to drain your account. In the former case, they'll happily allow you to overdraft your account, within limits, because it's profitable for them. In the latter, there is insurance to cover this loss, usually. I wouldn't call this a race condition in the programming sense. All of those withdrawals will be applied to your account. And banks will usually happily allow you to overdraft, again, because it's profitable. But within a limit.

As for depositing a check, the money they make available to you immediately is essentially credit. They will give you this credit for a certain amount, but there is a limit. For example, try to write yourself a check for $1M and then take it out immediately and you won't be able to do that.

There are all kinds of networks that money flows over. Probably the best known is ACH.