> they seriously stored user data in a Postgres database instead of a highly scalable cluster of NoSQL Cassandra instances

Erm …. Not sure I can post on this site knowing my posts are being stored in a SQL database on RDS

lol! Your post is actually stored (canonically) in your own individual SQLite database as of this week! We're in the process of moving our v1 Postgres-based backend to our v2 ScyllaDB-based backend.

Aha I was just joking around! That’s actually very cool - scyllaDB is an improvement over Cassandra if I remember correctly?

Yeah, I saw that, but it's actually pretty much impossible to do what we're doing with Postgres efficiently (and cost effectively). Yeah, ScyllaDB is basically a C++ rewrite of Cassandra with many operational improvements. I respect Cassandra but wouldn't run it myself.