TurboKV: Insanely fast Rust key-value store (github.com)
37 points by rgbimbochamp 2 hours ago
dangoodmanUT an hour ago
> DbOptions::durable()
> Appended to the WAL without a per-write sync
So… it’s not durable? Durable doesn’t mean “survives a process restart”, it means “durably saved to persistent storage”. For example, this “durable” mode wouldn’t survive power loss.
stingraycharles 42 minutes ago
Yeah this should be benchmarked against other systems that have flush() disabled.
mmap is nice but it doesn’t support durable semantics in the way that we usually mean with databases.
if a write is acknowledged it should not be forgotten, which is not what this is.
rgbimbochamp 29 minutes ago
You're right, that mode provides process crash recovery, not power-loss durability. The benchmark compares it against fjall’s equivalent buffered-WAL mode.
a2ff6eeb0 9 minutes ago
boguscoder 4 minutes ago
Embedded could also mean no_std, which this is absolutely not. Still cool though
nine_k an hour ago
I suppose the insane speed is due to this:
> TurboKV's persisted Bloom-filter format uses hardware AES.
Also, built-in LZ4 compression.
I would expect SIMD to be used for scans.
haberman an hour ago
I assume this is for hashing. I've seen several hashing algorithms turn to hardware AES instructions before, but I haven't seen any evidence that this technique outperforms state-of-the-art hashes like RapidHash (https://github.com/Nicoshev/rapidhash) in either quality or speed.
rgbimbochamp an hour ago
Those help but the main write speed gain is the WAL, that uses preallocated mmap segments to avoid a write(2) per durable mutation while preserving crash recovery. AES hashing mainly helps Bloom filter point lookups and LZ4 mainly helps SSTable I/O. Scans benefit indirectly, but don’t yet use a custom SIMD merge loop.
bestouff 21 minutes ago
I said elsewhere this doesn't survive a power loss.
taneq 17 minutes ago
dangoodmanUT an hour ago
Iirc that’s how badger handles the WAL as well