Open any textbook on databases and you’ll quickly learn that databases are slow because they write to physical disks. But with the latest NVMe drives, correct amortisation patterns, Direct I/O and strategic use of fsync, a well designed write pipeline is actually CPU bound. We’ll walk through the optimisations in Celeriant – an open-source event sourcing database built with io_uring, thread-per-core, Rust, and kernel-offloaded TLS – that push durable, replicated writes to more than 500k/sec; 15x Kafka on identical EC2 hardware.
