Just like I commented on the original incident report post, I think systems like Redis are not suitable to work as a db for payment processing and transaction s

Just like I commented on the original incident report post, I think systems like Redis are not suitable to work as a db for payment processing and transaction storage. Reading through the report I can't imagine something like this happening with a payment system built around Postgres. Not unless you are doing something incredibly stupid. And stupid those guys are not. They are obviously bright guys meaning well, and yet they've designed and implemented payment system with such a bad failure mode. I do understand that they have a LOT of billing events, and have to update customer billable amounts for each of them. But instead of holding the customer balances in Redis and doing payment processing on top of that, my paranoia would most probably lead me to only store 'amount to charge' in Redis and update it as frequently as needed, and store customer balances and transactions in an RDBMS. And only change during actual charge event. This way, if Redis data were to be lost, I'd under-charge my customers and not over-double-tripple charge them. The failure mode becomes less disastrous.