Indeed - seeing account balance used as an example of database transactions is a red flag to me, and would absolutely cause me to dig deeper into whether the author/speaker understands how banking actually works.
I don’t claim to be a banking expert, but I did work at a payment processor that handled real money, and we used “select for update” extensively.
We also (obviously) used a ledger, but “just let everyone overdraft whenever” wasn’t something that the executives of the company thought was a good idea. So we did try and prevent insufficient funds errors as much as possible.
I personally witnessed several scenarios where the company lost a notable amount of money, (not only rated to concurrency bugs of course) and it’s a pretty bad feeling.
Anyway, I’m legitimately curious to know from people who worked at larger banks perhaps. How is weak transaction isolation not a problem for banks?
I don’t claim to be a banking expert, but I did work at a payment processor that handled real money, and we used “select for update” extensively.
We also (obviously) used a ledger, but “just let everyone overdraft whenever” wasn’t something that the executives of the company thought was a good idea. So we did try and prevent insufficient funds errors as much as possible.
I personally witnessed several scenarios where the company lost a notable amount of money, (not only rated to concurrency bugs of course) and it’s a pretty bad feeling.
Anyway, I’m legitimately curious to know from people who worked at larger banks perhaps. How is weak transaction isolation not a problem for banks?