Mysqlex

A native MySQL driver for Elixir

A from-scratch implementation of the MySQL client/server protocol on top of db_connection — no C driver, no :mysql Erlang library.

Talk

This project is the companion to my talk at Functional Conf 2019: Building a MySQL Database Driver in Elixir (FnConf19).

Status

Work in progress. The connection phase is partially implemented: the driver connects over TCP and reads the server's Protocol::HandshakeV10 packet. The command phase callbacks return an error until that work lands.

The goal is to implement everything in the protocol that can be implemented — text and binary protocols, every auth plugin, prepared statements, cursors, transactions, replication — rather than the shortest path to a working query. An Ecto integration is a someday goal on top of that.

See ROADMAP.md for the plan, phase by phase, and for how to pick this up: local server setup, capturing real packets as test fixtures, and the reference implementations worth reading.

Installation

This is a personal project rather than a library, and it is not published to Hex. To try it from git anyway:

def deps do
  [
    {:mysqlex, github: "balaghdev/mysqlex"}
  ]
end

Development

Runtime versions are pinned in .tool-versions (mise or asdf):

mise install          # Erlang 27.3.4.15 + Elixir 1.20.4
mix deps.get

mix test                      # Tests
mix format                    # Format
mix credo --strict            # Lint
mix dialyzer                  # Type check
mix docs                      # Generate docs with ExDoc
mix compile --warnings-as-errors

CI runs the same checks across Elixir 1.20.4 (OTP 27 and 28) and 1.17.3.

Protocol reference

The MySQL protocol documentation this is built against is vendored under docs/mysql-protocol/ — packet layouts, capability flags, auth methods and command reference, converted to markdown with links back to the upstream pages.