We also hit scaling problems with temporal.

Postgres doesn't scale at all four our workload, so you're into cassandra.

For a medium sized deployment, you're looking at 200+ vcpus, and then lets say standard dev/uat/prod. So now you're at 600 cpus. Now you need two geographic regions, dev can stay in one place, so now you're at 800. Want a failover cluster for prod? Have another 200 cpus.

and 200 CPUs is a medium deployment, assuming something like 36 cpus per cassandra node, then say 4-8 per instance of matching, worker, history, frontend. Then all your other components around it, ingress controller, service mesh, etc.

There's a million a year easy, for a small deployment.

Our prod one is 4x this size.