Hello, there is a Rust SQL crate called clorinde (a fork of cornucopia) where you write queries like this:

--: Author(age?)
--! authors : Author
SELECT name, age FROM Authors;
--! authors_from_country (country?) : Author
SELECT name, age
FROM Authors
WHERE Authors.nationality = :country;

(Example taken from here)

And then clorinde, using the database schema, generates ergonomic Rust code that performs those queries.

The queries are in a format that is almost suitable for postgres-language-server, except that with it you write parameters :likethis rather than the usual ? or 1ドル syntax used in prepared statements and SQL functions respectively. So at minimum there should be support in the parser for this syntax, and this limited support would be extremely useful already.

But also, the function signatures provided by clorinde can aid the postgres lsp: country? there means that country is nullable (in the Rust side, it's an Option). And I would like to hover the country parameter and have the IDE tell me its type (in this case, it depends on the column nationality of table Authors).

Maybe this is not appropriate for the postgres lsp, and as such it would be necessary to create a language server specific for clorinde - but the postgres lsp does 95% of the job already, and I think it's a good fit.