pqi-native

Status: Alpha. pqi-native is an early implementation of a pure-Haskell transport for pqi. It exists alongside pqi-ffi, the established C-backed adapter, and the two are fully interchangeable: any code written against pqi runs unchanged on either one, so trying pqi-native carries no lock-in and no rewrite cost. Correctness is checked continuously against a conformance suite (see below), but the adapter hasn't yet accumulated production mileage. If you need a production-proven transport today, use pqi-ffi. See Making libpq a choice for why this project exists and what tradeoffs that implies.

A pure-Haskell pqi adapter that speaks the PostgreSQL frontend/backend wire protocol directly — no dependency on the C libpq library.

pqi-native reimplements the wire protocol handled by the PostgreSQL C client library, libpq, from scratch in Haskell. The upstream libpq source is the direct reference for the implementation.

Fidelity goal

The goal is byte-identical output to libpq for every protocol-derived value — error message strings, notice text, result status, field metadata, cell data, and all structured error fields. Fidelity is continuously enforced by pqi-conformance, which runs every operation on both this adapter and a direct postgresql-libpq reference connection against the same database and asserts exact equality.

Status

Alpha. The full Pqi.Connection capability record is implemented and verified against the postgresql-libpq reference via the conformance differential suite, but the library hasn't yet accumulated real-world production mileage.

Because it implements the same pqi interface as pqi-ffi, switching between the two is a one-line change — pass a different Adapter value, nothing else in your code moves. That makes pqi-native low-risk to evaluate now and easy to fall back from: adopt it where you want to shed the libpq dependency, and drop back to pqi-ffi at any time without touching the rest of your codebase. Read Making libpq a choice for the motivation and the tradeoffs of adopting it at this stage.

Authentication: trust, MD5, and SCRAM-SHA-256 are implemented. SCRAM is verified against a password-auth PostgreSQL 17 container (which defaults to scram-sha-256).