rgbimbochamp

RocksDB’s default is WriteOptions.sync = false. It can lose recent acknowledged writes after power loss, much like TurboKV Durable. Most folks use that unknowingly.

durable() syncs periodically on flush, WAL rotation, and clean close; paranoid() is the sync-before-ack mode. This is clarified in the README, and the benchmarks report all three modes separately. Other KV-stores that you see on the market, do this too. It's a performance tradeoff most applications make. Sync on every write kills every optimization. See the benchmark table for example.

paranoid() does survive power loss.

You're right, that mode provides process crash recovery, not power-loss durability. The benchmark compares it against fjall’s equivalent buffered-WAL mode.

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.