By early 2015 we had both Chronicle Queue and Kafka in production — Chronicle for intra-day trade journaling, Kafka for end-of-day data pipelines. The question came up repeatedly: why not use one for both? The answer is that they solve different problems with incompatible design priorities. ...
Every trade needs to be journaled. You need a durable, ordered record of every order, fill, and state change — for risk, reconciliation, and regulatory purposes. The naive solution is a database write on the hot path. That’s a roundtrip to an external process, a network call, and often a disk fsync. It’s also hundreds of milliseconds of latency per event. Chronicle Queue gave us persistent journaling at sub-microsecond overhead. Here’s how. ...