This post makes a great case for how universal logs are in data systems. It was strange to me that there was no log-as-service with the qualities that make it suitable for building higher-level systems like durable execution: conditional appends (as called out by the post!), support very large numbers of logs, allow pushing high throughputs with strict ordering, and just generally provide a simple serverless experience like object storage. This led to https://s2.dev/ which is now available in preview.

It was interesting to learn how Restate links events for a key, with key-level logical logs multiplexed over partitioned physical logs. I imagine this is implemented with a leader per physical log, so you can consistently maintain an index. A log service supporting conditional appends allows such a leader to act like the log is local to it, despite offering replicated durability.

Leadership can be an important optimization for most systems, but shared logs also allow for multi-writer systems pretty easily. We blogged about this pattern https://s2.dev/blog/kv-store