Comment by solatic
23 days ago
> real-time usage -> billing
This is one of the things that excites me about TigerBeetle; the reason why so much billing by cloud providers is reported only on an hourly granularity at best is because the underlying systems are running batch jobs to calculate final billed sums. Having a billing database that is efficient enough to keep up with real-time is a game-changer and we've barely scratched the surface of what it makes possible.
Thanks for mentioning them, we're doing quite similar debit-credit stuff as https://docs.tigerbeetle.com/concepts/debit-credit/ but reading https://docs.tigerbeetle.com/concepts/performance/ they are definitely thinking about the problem differently from us. You need much more prescribed entities (eg resources and skus) on the modelling side and different choices on the performance side (for something like a usage pricing system) for a cloud platform.
This feels like a single-tenant, centralized ACH but I think what you actually want for a multitenant, multizonal cloud platform is not ACH but something more capability-based. The problem is that cloud resources are billed as subscriptions/rates and you can't centralize anything on the hot-path (like this does) because it means that zone/any availability interacting with that node causes a lack of availability for everything else. Also, the business logic and complexity for computing an actual final bill for a cloud customer's usage is quite complex because it's reliant on so many different kinds of things, including pricing models which can get very complex or bespoke, and it doesn't seem like tigerbeetle wants calculating prices to be part of their transactions (I think)
The way we're modelling this is with hierarchical sub-ledgers (eg per-zone, per-tenant, per-resourcegroup) and something which you could think of as a line of credit. In my opinion the pricing and resource modelling + integration with the billing tx are much more challenging because they need to be able to handle a lot of business logic. Anyway, if someone chooses to opt-in to invoice billing there's an escape hatch and way for us to handle things we can't express yet.