This would not work at scale for a company like Discord, with its volume of traffic. Cockroach, being consistency-oriented would quickly become transaction-bound. You want a database like a Cassandra or Scylla that is more performance/availability oriented. Otherwise you are going to see a lot of lag and latency in the Discord chat.

Cockroach is very, very good for a distributed SQL database. But it's still performance-limited in its very nature.

More here on the difference between NoSQL/NewSQL performance, using Scylla (a CQL-workalike) as a point of comparison:

https://www.scylladb.com/2021/01/21/cockroachdb-vs-scylla-be...

On the day that this blog post was written, CockroachDB was only at beta-20170112 and didn't even had a production release yet.

v1.0 was released on May 10, 2017 [1], so I doubt it was even on their mind when they started working on the project.

[1] https://www.cockroachlabs.com/docs/releases/index.html