Glad you like it!

You don't need to recompile it actually! It's enough to compile your extension and Postgres can then dynamically link to it, which makes for a perfectly good feedback loop. pgfdb is built with pgrx: https://github.com/pgcentralfoundation/pgrx, which is a framework for building Postgres extensions in Rust that handles all the compiling and linking for you. Highly recommend that if you want to try writing extensions and are also a fan of Rust!