I think this ACID-based approach is a reasonable way to achieve exactly-once message processing, as long as one is happy to limit that guarantee to only DB operations.

If anyone is interested in a failed attempt to implement this you can see my write up [1]. It contains some learnings from the experimental implementation I created for Lightbus.

The implementation was based on this presentation [2]

[1]: https://github.com/adamcharnock/lightbus/issues/4

[2]: https://vimeo.com/111998645