QuackDB

Remote DuckDB Quack protocol client for Elixir.

quackdb is a protocol-native client for DuckDB's experimental Quack remote protocol. The client is backed by DBConnection, decodes DuckDB result chunks directly, supports streaming/fetching large result sets, and includes an initial Ecto adapter for raw SQL queries.

[!WARNING] QuackDB itself is experimental and not production-ready. The package API, result shapes, Ecto adapter behavior, and supported type coverage may change as the project evolves. It also targets DuckDB's experimental Quack protocol, which may change across DuckDB releases. Use it at your own risk, validate behavior against your DuckDB version, and avoid relying on it for critical production workloads yet.

Status

QuackDB currently focuses on the remote protocol and DBConnection client core. It supports:

• connection handshake over HTTP Quack endpoints
• query execution through DBConnection
• streaming and fetch continuation for large results
• common scalar DuckDB types
• nested result values such as LIST, STRUCT, ARRAY, and MAP
• normalized affected-row counts for INSERT, UPDATE, and DELETE
• a minimal Ecto SQL adapter for Repo.query/3

Higher-level Ecto schema queries, migrations, and write planning are planned after the raw SQL adapter path is stable.

Installation

Add :quackdb to your dependencies:

def deps do
  [
    {:quackdb, "~> 0.1.0"}
  ]
end

DuckDB's Quack protocol is currently experimental. For local testing, use DuckDB 1.5.3 or newer with the quack extension.

Start a DuckDB Quack server

tail -f /dev/null | duckdb -init /dev/null \
  -cmd "LOAD quack; CALL quack_serve('quack:localhost', token='super_secret');"

quack:localhost may bind on IPv6 localhost, so the examples use http://[::1]:9494.

Usage

Connect

{:ok, conn} =
  QuackDB.start_link(
    uri: "http://[::1]:9494",
    token: "super_secret"
  )

Query

{:ok, result} = QuackDB.query(conn, "SELECT 1 AS n")

result.columns
#=> ["n"]

result.rows
#=> [[1]]

Results use compact IEx-friendly inspection so large result sets do not flood the console:

#QuackDB.Result<command: :select, columns: ["n"], rows: 1, preview: [[1]], connection_id: "...", needs_more_fetch?: false>

Nested DuckDB values

DuckDB nested types decode to ordinary Elixir terms:

{:ok, result} =
  QuackDB.query(conn, """
  SELECT
    [1, 2, 3] AS xs,
    {'name': 'duck', 'count': 2} AS obj,
    array_value(1, 2, 3) AS arr,
    map(['a', 'b'], [1, 2]) AS m
  """)

result.rows
#=> [[[1, 2, 3], %{"name" => "duck", "count" => 2}, [1, 2, 3], %{"a" => 1, "b" => 2}]]

Streaming

Use QuackDB.stream/4 for large result sets:

row_count =
  conn
  |> QuackDB.stream("SELECT i FROM range(0, 50_000) t(i)")
  |> Enum.reduce(0, fn result, count -> count + result.num_rows end)

row_count
#=> 50_000

Command results

DuckDB returns affected-row counts through a Count column. QuackDB normalizes those into num_rows for command results:

{:ok, _} = QuackDB.query(conn, "CREATE TEMP TABLE events(id INTEGER)")
{:ok, result} = QuackDB.query(conn, "INSERT INTO events VALUES (1), (2)")

result.command
#=> :insert

result.num_rows
#=> 2

result.rows
#=> nil

The original DuckDB shape is preserved in metadata for debugging:

result.metadata[:duckdb_columns]
#=> ["Count"]

result.metadata[:duckdb_rows]
#=> [[2]]

Prepare and execute

{:ok, query, result} = QuackDB.prepare_execute(conn, "SELECT 1 AS n")

query.columns
#=> ["n"]

result.rows
#=> [[1]]

Ecto raw SQL

QuackDB includes an initial Ecto SQL adapter for raw SQL queries. If your app does not already depend on Ecto SQL, add it alongside QuackDB:

def deps do
  [
    {:quackdb, "~> 0.1.0"},
    {:ecto_sql, "~> 3.13"}
  ]
end

Then define a repo:

defmodule MyApp.AnalyticsRepo do
  use Ecto.Repo,
    otp_app: :my_app,
    adapter: Ecto.Adapters.QuackDB
end

Configure the repo with the same connection options used by QuackDB.start_link/1:

config :my_app, MyApp.AnalyticsRepo,
  uri: "http://[::1]:9494",
  token: "super_secret"

Then use Repo.query/3:

{:ok, result} = MyApp.AnalyticsRepo.query("SELECT 1 AS n")

result.rows
#=> [[1]]

Raw SQL also works inside Ecto transactions:

{:ok, :committed} =
  MyApp.AnalyticsRepo.transaction(fn ->
    MyApp.AnalyticsRepo.query!("CREATE TEMP TABLE events(id INTEGER)")
    MyApp.AnalyticsRepo.query!("INSERT INTO events VALUES (1), (2)")
    :committed
  end)

Use Repo.rollback/1 to abort transaction work:

{:error, :rolled_back} =
  MyApp.AnalyticsRepo.transaction(fn ->
    MyApp.AnalyticsRepo.query!("INSERT INTO events VALUES (3)")
    MyApp.AnalyticsRepo.rollback(:rolled_back)
  end)

Simple read-only Ecto queries against table names are also supported:

import Ecto.Query

MyApp.AnalyticsRepo.all(
  from event in "events",
    where: event.id > 1,
    order_by: [asc: event.id],
    select: %{id: event.id, name: event.name}
)

This first Ecto milestone is intentionally limited. Joins, grouped queries, migrations, and Ecto-managed inserts/updates/deletes raise explicit unsupported-feature errors for now.

Current limitations

• Bind parameters are not exposed through this Quack client path yet.
• Appends are represented at the protocol struct level but are not exposed as public API.
• Ecto support is limited to raw SQL through Repo.query/3 and simple read-only table queries through Repo.all/2.
• The low-level protocol is experimental and tracks DuckDB's Quack extension behavior.

Development

mix deps.get
mix ci

Integration tests are skipped by default. To run them against a Quack server:

QUACKDB_TEST_URI='http://[::1]:9494' \
QUACKDB_TEST_TOKEN=super_secret \
mix test --include integration

See guides/getting-started.md for a longer walkthrough and docs/research.md for protocol notes.