A novel O(1) Key-Value Store - CandyStore

Sweet Security has just released CandyStore - an open source, pure Rust key-value store with O(1) semantics. It is not based on LSM or B-Trees, and doesn't require a journal/WAL, but rather on a "zero overhead extension of hash-tables onto files". It requires only a single IO for lookup/removal/insert and 2 IOs for an update.

It's already deployed in thousands of Sweet's sensors, so even though it's very young, it's truly production grade.

You can read a high-level overview here and a more in-depth overview here.