ducksdb-mysql-engine

An in-tree DuckDB storage engine for MySQL 9.7.

Create a table with ENGINE=DuckDB and analytical queries against it execute inside DuckDB's columnar/vectorized engine automatically — no SECONDARY_ENGINE= / SECONDARY_LOAD ceremony. One server, one SQL interface.

The engine is built into mysqld as a MANDATORY storage engine and registers a small server hook (handlerton::pushdown_select, added by the patches in server-patches/) that lets it take over execution of a whole SELECT whose base tables are all ENGINE=DuckDB: the query is regenerated in DuckDB's dialect, run in DuckDB, and the result streamed back. Anything it can't translate declines transparently and falls back to normal MySQL execution.

The pushdown covers aggregates, inner/outer joins, derived tables, CTEs, scalar subqueries, and IN / EXISTS / NOT IN / NOT EXISTS predicates — all 22 TPC-H queries push down and return results identical to InnoDB. On SF10 the engine is on par with MariaDB's ENGINE=DuckDB (see docs/tpch_sf10_mariadb_comparison.md).

Run with Docker

A prebuilt image ships MySQL 9.7 with the engine already built in:

docker run -d --name mysql-duckdb -p 3306:3306 \
  -e MYSQL_ROOT_PASSWORD=secret \
  -v mysql-duckdb-data:/var/lib/mysql \
  evgeniypatlan/test-images:mysql-9.7-duckdb-v0.2.0

mysql -h 127.0.0.1 -u root -psecret -e "
  CREATE DATABASE shop; USE shop;
  CREATE TABLE sales (id INT PRIMARY KEY, region INT, amount DECIMAL(12,2)) ENGINE=DuckDB;
  INSERT INTO sales VALUES (1,1,100),(2,1,200),(3,2,50);
  SELECT region, SUM(amount) FROM sales GROUP BY region;"

See docs/installation.md for configuration and persistence, and docs/usage.md for the full query guide.

Layout

• engine/ — the handler (ha_duckdb) and the whole-query pushdown (duckdb_pushdown).
• common/ — the shared storage/type/DML/transaction/util layer.
• server-patches/ — the MySQL server patches the engine depends on (applied into the build tree by scripts/build-server.sh).
• cmake/ — DuckDB acquisition (prebuilt prefix, or built from source via ExternalProject).
• engine/test/ — standalone GoogleTest/CTest unit suite.
• mysql-test-suite/ — MTR tests (suite=duckdb).
• bench/ — benchmark harness (InnoDB vs the DuckDB engine).

Build & test

scripts/build-server.sh     # configure + build mysqld with the engine
scripts/run-mtr.sh          # MTR suite=duckdb
engine/test/run-tests.sh    # unit tests

DuckDB is resolved from a prebuilt prefix (DUCKDB_ROOT / vendored vendor/duckdb-prefix) when available, otherwise built from source — so a clean checkout builds with no DUCKDB_ROOT set.