Show HN: KantoDB, a Postgres-compatible OLTP database using DataFusion and Rust (kantodb.com)

I'm writing a brand-new OLTP database with Rust, DataFusion and RocksDB. It's both a Postgres-compatible SQL server and a Rust library that takes SQL and returns Arrow RecordBatches[0]. Apache-2 licensed.

Close enough to Postgres that apps think it's Postgres, but also runnable as a library like SQLite -- best of both worlds! And then if you're willing to not limit yourself to Postgres compatibility, you also get fancy new technologies like unsigned integers in a database! (Old SQL ecosystem is sometimes ridiculous.)

It's still very early days, but it's exciting! The darn thing already works as a SQL database — largely because it’s just DataFusion’s query engine and me feeding it table scans. I wrote a SQL database without ever debugging a JOIN! The shortcuts I’ve been able to take due to help from preexisting projects are huge. For someone who grew up in the world of "every C project has to write basic data structures for themselves because C isn’t very modular", it’s downright amazing!

Next up, I am looking to identify significant open source projects with automated integration test suites[1], and classify our success based on how many of those won’t even realize they are not running on Postgres. Errors encountered will help determine priorities for development.

[0]: FFI from C/Python/Typescript/whatever to come later, Arrow makes that pretty easy, it's designed to be a platform- and language-agnostic in-memory data structure.

[1]: Rough integration test criteria for a project to be easy for our integration testing: has automatable pass/fail outcome (not manual use of web UI), tests actually talk to Postgres and don't fake it, open source, easily runs in a single plain container, is not a muddy pile of multiple microservices that need to be orchestrated, reports errors clearly, relatively popular or small and simple.