Just wondering if anyone considered using Postgres or another relational db. I understand it won’t do multi master replication as well but it is much more stable and predictable if you give it right amount of traffic. I guess the team had to do that part anyways for ScyllaDB
I don't think anyone runs Postgress at that scale (unless very specialized sharding setup). Given the choice between using ScyllaDB like everyone else and using Postgres in a super specialized best in the world setup, the choice becomes clear. Also keep in mind that Discord is not a huge super profitable company, so for them to develop something like vitess for Postgress would not make sense. For a small company with huge data like discord, using existing data solutions makes a lot more sense.
They could use vitess, citus or alloydb. They could use read replicas for read operations and single master in a shard for write. They would get many SQL features (upgrades, referential integrity etc) for free. It would allow them to extend their business logic considerably.
