letter_box VS bonsaidb

I do have ideas in the issue tracker on some of the next steps towards an actual migration system.

What about https://github.com/khonsulabs/bonsaidb? Progress seems stall since last summer but very cool project

There is Nebari which is the KV part of BonsaiDB I've used both successfully (and that is currently in production)

In BonsaiDb, I define entire test suites as macros. This crate has a common trait that has multiple implementations in different crates. Each implementation needs to be tested thoroughly. For cargo test to be able to work in each crate independently, I needed to have the #[test]-annotated functions in the crate being built. By using a macro, I can define the functions in one location and invoke the macro in each crate to import the test suite into that crate.

hey, just letting you know that there already is a project called bonsai-db and some people might confuse bonsai-bt as part of that project

I'm finishing up a large refactor of BonsaiDb which will add support for using BonsaiDb in non-async code.

I'm working on a major refactoring of BonsaiDb, aiming to improve the design of several interrelated features. While it started by aiming to enable a non-async interface for BonsaiDb, I realized mid-refactor that another major refactor would be better to do simultaneously rather than separately. Thank goodness that refactoring in Rust is such a wonderful experience!

It depends on what you mean by "support graphs". If you mean support the abillity to build a GraphQL interface in front of it, yes that is already possible in a limited fashion, although there are no first-class relationship types yet.

I'm trying to release the first alpha of BonsaiDb. I'm wrapping up replacing OPAQUE with Argon2, in an effort to make upgrading less likely to cause issues in the future (given that OPAQUE is still a draft protocol). I still love OPAQUE and will bring it back in the future.