In this case, the features we kept getting asked for by our customers necessitated a change in underlying database architecture. I talk about that quite a bit in the reddit thread.

I totally agree that a rewrite is risky. It's not something I'd choose to do again, but at the time we didn't really see any way around rewriting the bulk of the database (even if we kept it implemented in Go).

Using Rust and the Arrow ecosystem of projects (Parquet, DataFusion, Flight) meant that there were a ton of things we didn't have to do from scratch. One of our staff engineers, Andrew Lamb, has called it a toolkit for building databases. Thanks in part to his contributions, I think he's right.