https://github.com/k3s-io/kine#readme but it's "caveat emptor" since to the best of my knowledge no one runs conformance tests on top of it

I could spent >0s looking into this, but I've been curious how kline implements Etcd's Watch API[1]. For the matter, I don't have much idea in general how kline handles data. Kline would be a great candidate for a blog post or introductory technical article on.

I do quickly see one issue- evidently watches presently use polling. The issue requests use of postgres triggers[2].

[1] https://etcd.io/docs/v3.2/learning/api/#watch-api

[2] https://github.com/k3s-io/kine/issues/20