I'm using fjall v2 in the Rust event streaming store, cross.stream (`xs`) https://github.com/cablehead/xs

`xs` is for personal scale so fjall is fairly overkill performance-wise. marvin_j97's benchmark work and deep dives into different database systems is incredible though. Looking forward to updating to v3.

I've built an event-sourcing/stream framework on top of Fjall v3, and it's been a fantastic fit. It's a great building block for many systems where a more high-level storage system is either overkill or a poor match for the access patterns you actually have (in my case, sequential access to prefix-filtered data gets you 95% of the way to an efficient persistent stream). I started trying to layer things on top of PostgreSQL and similar, and the impedance mismatch and resultant unpleasant code (and performance!) made me look elsewhere.

Fjall is an LSM-based key-value store written in Rust. It is pretty similar to RocksDB.

I do wish to note also that Marvin's blog posts are very informative and a great read. I would highly suggest reading them if you are at all interested in how Fjall or other LSM-based storage engines work.