Idea
A distributed key-value store kept as small as it can be: one node per shard replica, a single-file Bitcask, Raft with elections and log replication only, and fixed hash sharding. About 830 lines of Rust in one crate.
How it works
- Sharding. Sorted node ids are cut into runs of
rf, one shard per run. A key’s shard isfnv1a(key) % shards, and a node that gets another shard’s key redirects. - Replication. Every shard is its own Raft group, so shards share nothing and scale by adding
rfnodes. Raft itself does no I/O: it changes state and queues messages. - Linearizable reads. Reads go through the log just like writes.
- Durability. New log entries and the vote are written as one batch and fsynced on a separate thread. Nothing is acknowledged before it is on disk.
- Storage. One append-only file per node:
crc32 | key_len | value_len | key | value, with an in-memory index.
More
A full-featured branch adds snapshots, membership changes, shard migration, wait-free reads and a deterministic simulator.