[phamilton]

Just sharing a data point and experience.

We had a lot of success with LISTEN/NOTIFY when we paired it with a Rust graphql subscription broker. 10s of thousands of subscriptions, but only 3 or 4 LISTEN connections (one for each host). All changes would be pushed out to all hosts, who would each manage the actual user subscriptions and choose what to actually publish.

This worked super well. In general, moving from hundreds of Ruby or Node hosts to just a few Rust hosts just allows so many simplifications and things that "don't scale" to actually work quite well.

[hoodaly]

I‘m interested, which graphql library for Rust can you recommend?

[phamilton]

Any graphql library would work. I like async-graphql except compilation is a bear due to all the macros. We wired LISTEN up to subscriptions using tokio mpmc channels. It was a great moment of "fearless concurrency", it all just worked.

[rneswold]

I like 'async-graphql'. I tried 'juniper' but, at the time, it didn't have as many features. That may have changed over the last year or so since I looked at it.