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Good point. But I'd argue that's an artifact of history. Traditional banks started out when eventual consistency was the only choice. First with humans manually
by wongarsu 2y ago
Good point. But I'd argue that's an artifact of history. Traditional banks started out when eventual consistency was the only choice. First with humans manually reconciling paper ledgers based on messages from couriers and telegraphs, later with the introduction of computers in batch processes that ran over night. The ability to do this live is new to them, and thus their processes are designed to not require it.
Financial institutions set up in this century (like paypal or fintecs) usually do want consistency at all cost. Your risk exposure is a lot lower if you know people don't spend or withdraw more than they have.
- darby_nine 2y ago> Good point. But I'd argue that's an artifact of history. I think there's also less liability for the banks if they accept and build around the risk of both eventual consistency and fraud. Even now wiring is necessary to pull off a digital bank theft, and even then you need to be extremely fast to get away with the money, and extremely fast to not go to prison, and liquidate it extremely quickly (likely into bitcoin). Even small delays in the transactions would make this basically impossible with modern banking, let alone a full clearing house day.
- dalyons 2y agofintechs have some inhouse tech but typically involve all kinds of third party systems. Even if you are interacting with these third parties via apis(instead of csv or whatever), you will always need an eventually consistent recon mechanism to make sure both sides agree on what was done. It doesnt have to take days though i agree. The only way around this would be to replace stateful apis with some kind of function that takes a reference to a verifiable ledger, that can mutate that and anyone can inspect themselves to see if the operation has been completed. Oh wait :)
- pradn 2y agoEventual consistency gives you more availability, at the cost of consistency. It's fine for financial institutions to prefer this trade-off, because the any over/under error is a likely a fraction of the cost of unavailability. Also, in the real world, we can solve problems at a different level - like legal or product.
- PaulHoule 2y agoAlso the financial institutions are making enough profit that they can afford to lose a little bit in the process of reconciliation. Consider how the 3.5% fees credit cards charge mean they can afford to eat a bit of fraud and actually can tolerate more fraud than a system which had lower fees could.
- cameronh90 2y agoRequiring availability sounds like a good recipe for global payment system outages. It also makes it a lot harder to buy things on a plane.