diesel_async VS metrics

So I want to use diesel_async in my web backend.

The already linked discussion from last time already contains a lot of information about this. Diesel itself does not provide async operations and that will likely remain that way for a foreseeable future. At least my preferred solution is to keep async support in a separate crate. A prototype for this is currently available here. Keep in mind that this is not released yet, so there might be bugs everywhere. I plan to cut a first release of this crate after the final release of diesel 2.0, which means hopefully soon. As for ETA's: I generally do not give any ETA's for releases, as this is currently a free time project for me.

So, diesel is an ORM that tries to take full advantage of rust's typing expressivity to allow for statically checked, and fast, queries. I absolutely loved it when trying it out the first time.

i don't see why you or anyone else would consider it too big of an issue that Diesel doesn't have async. For those who really want async diesel right now, the author already released diesel_async as a stop-gap solution, but even without that there's nothing wrong with using spawn_blocking. It feels worse than it really is to use blocking thread pools; until io_uring is a thing, there's no real getting around the necessity of threads being blocked for I/O and so adding async to the mix doesn't magically make things faster.

As for now there is an prototype available here. It's technically feature complete, but depends on a unpublished diesel version + has some remaining bugs with certain mysql versions. If that is fixed I will likely publish a first alpha version officially. That can take same time because that's a second large project that needs maintenance time beside diesel itself and that's quite a lot to do in my free time. You can support this work by sponsoring me on github

Async support for diesel currently lives in a separate repository as there are language level blocking issues for publishing a version of this crate where we could commit to a stable release at all. See the corresponding diesel issue for details.

https://github.com/weiznich/diesel_async tho'.

Weiznich (the maintainer of Diesel) has created an experimental async version of the diesel Connection and RunQueryDsl traits, which should help with ease-of-use for Diesel within async contexts. It is not yet published on crates, but you can find it here: https://github.com/weiznich/diesel_async

It's worth keeping an eye on Diesel's metrics suite (https://github.com/diesel-rs/metrics) as well; I found and fixed some suboptimal buffering that was affecting performance.

See here for some numbers. The relevant code lives inside the diesel github repository. Please also keep in mind that these are just numbers and you should run those these on your own and also run tests with your actual work load.

Performance is worse than in comparable frameworks

For the database part you might want to checkout a crate that's not based on sqlx as sqlx is known for providing non-optimal performance for the sqlite backend. rusqlite or diesel perform much better for this use case.

No it will likely not be less performant. See these numbers for some benchmark results for numbers. (As always with benchmarks: Please don't trust my numbers. To be sure you need to do your own benchmarks with your own use-case)

See here for some benchmark results. The benchmarks itself are in the diesel repository. Otherwise I believe there are numbers in the techempower benchmarks as well, although that includes other factors .

I'm developing a Rust web server backend in Axum that uses Postgres and performance will be pretty important since I plan to run it on one server for as long as possible. It seems like the postgres crate is about 2x faster than sqlx, and the postgres repository seems pretty active still.

Congratulations to the release. I know all of this is hard work. I would like to invite you to submit a ormlite implementation to the diesel benchmark collection. As soon as that's merged you will get regular reports here. The relevant code is here in the diesel repository.

In that case you may be interested in the metrics for different database libraries. diesel is doing rather well at the moment. sqlx is in the middle of a large rewrite that should improve performance, so we'll see how it compares after that

See here for some benchmark results for the diesel repository. Please keep in mind that as always with benchmarks, these numbers are not necessarily true for your usecase. Be sure to checkout at least the benchmark code and draw your own conclusions from there.