These are certainly valid considerations, but I would like to point out that just because a project seems large on the outside that does not guarantee that it has enough maintainers. Most open source projects are still run by a single person. That is still mostly the case for diesel, but also applies to much larger projects like curl. So while it might feel like a „large“ project will protect you from such issues, that’s really no sufficient guarantee. The only way you could make sure to not run into such problems is by auditing all of your dependencies.

While I can understand your concern, I‘m technically speaking also just some rando in the internet. It’s likely a better solution to evaluate crates a somewhat independently from their authors and and bit more on the actual code, quality and number of other projects dependent on such a crate. Sometimes such crates from someone in the community are real gems.

Well there are a few reasons not to have it in diesel itself. One is that the main crate already is really large. Adding another massive feature like that would make it make harder to maintain. I think about splitting up diesel into multiple parts instead from time to time. The other important reason is that diesel itself is stable, while diesel-async is still a bit in the flux due to the general instability of the async ecosystem and async rust in general. For example we still miss several language features like asynchronous drop or proper async closures that allow to reason about the future they return to provide an actual stable interface for diesel-async. While all of that likely will not result in a fundamental change in the provided interface it remains a breaking change to make adjustments as soon as these features exist and are stabilised. That’s incompatible with the stability guarantee given by diesel itself.

As for having it next to diesel itself: Technically these crates are still separate projects maintained by different set of peoples. Diesel itself is maintained by the diesel core team, where I happen to be a member of that team. That team has a limited amount of capacity. Diesel-async is maintained by myself in whatever time is left after the time I spend on diesel. Sure it would be possible to have it in the diesel organisation as well, but I honestly do not see the relevant capacity there yet. You are welcome to change that. See the linked blog post for details on how you can contribute to that.

diesel-async exists for several years now. It’s stable enough to be used by crates.io as database library for serving essential all crates in the rust ecosystem.

At this point I‘m not sure what else to do given that the crate is literally linked from the diesel home page, all relevant issues and literally every else this came up before. I‘m just not sure why people still believe that it doesn’t exist. So maybe someone would be able to explain that?