Looking for a Change Data Capture (CDC) lib for MySQL

My Elixir application needs to connect with a MySQL database and listen for insert and updates in certain tables, does anyone know about a library that makes this easier? I would use WalEx or Cainophile but they are intended for PostgreSQL DBs.

The MySQL driver doesn’t seem to support this functionality, so I don’t think you will have much luck finding other libraries around, unless you want to fork it and add your functionality there somehow.

I think your best bet is to use ports to integrate with another language that has support for listening for events, like IDK Java or maybe something more lightweight.


You could use Port — Elixir v1.16.3 with the stdout option of https://maxwells-daemon.io/

I have this proof of concept code that might get you started

defmodule MaxwellListener do
  use GenServer

  # Adjust the command to include the full executable path if necessary
  @command "maxwell"
  @args [
    "--filter='exclude: *.*, include: holdsport.users, include: holdsport.teams_users'",

  def start_link(opts \\ []) do
    GenServer.start_link(__MODULE__, :ok, opts)

  def init(:ok) do
    command_with_args = Enum.join([@command | @args], " ")
    options = [:binary, :exit_status]
    port = Port.open({:spawn, command_with_args}, options)
    {:ok, %{port: port}}

  def handle_info({port, {:data, data}}, state) do
    {:noreply, state}

  def handle_info({:EXIT, _port, _reason}, state) do
    # Handle port exit
    {:stop, :normal, state}

  defp process_output(data) do
    |> String.trim_trailing()
    |> Jason.decode!(keys: :atoms)
    |> handle()

  defp handle(%{table: "teams_users", data: %{users_id: user_id}}) do
    IO.inspect(user_id, label: "User ID")

  defp handle(d) do
    IO.inspect(d, limit: :infinity)
1 Like

Thank you! I will give it a try