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0.10 (stable)
MySQL Extension

The mysql extension allows DuckDB to directly read and write data from/to a running MySQL instance. The data can be queried directly from the underlying MySQL database. Data can be loaded from MySQL tables into DuckDB tables, or vice versa.

Installing and Loading

To install the mysql extension, run:

INSTALL mysql;

The extension is loaded automatically upon first use. If you prefer to load it manually, run:

LOAD mysql;

Reading Data from MySQL

To make a MySQL database accessible to DuckDB use the ATTACH command:

ATTACH 'host=localhost user=root port=0 database=mysql' AS mysqldb (TYPE mysql)
USE mysqldb;

The connection string determines the parameters for how to connect to MySQL as a set of key=value pairs. Any options not provided are replaced by their default values, as per the table below.

Setting Default
database NULL
host localhost
password  
port 0
socket NULL
user current user

The tables in the MySQL database can be read as if they were normal DuckDB tables, but the underlying data is read directly from MySQL at query time.

SHOW TABLES;
┌───────────────────────────────────────┐
│                 name                  │
│                varchar                │
├───────────────────────────────────────┤
│ signed_integers                       │
└───────────────────────────────────────┘
SELECT * FROM signed_integers;
┌──────┬────────┬──────────┬─────────────┬──────────────────────┐
│  t   │   s    │    m     │      i      │          b           │
│ int8 │ int16  │  int32   │    int32    │        int64         │
├──────┼────────┼──────────┼─────────────┼──────────────────────┤
│ -128 │ -32768 │ -8388608 │ -2147483648 │ -9223372036854775808 │
│  127 │  32767 │  8388607 │  2147483647 │  9223372036854775807 │
│ NULL │   NULL │     NULL │        NULL │                 NULL │
└──────┴────────┴──────────┴─────────────┴──────────────────────┘

It might be desirable to create a copy of the MySQL databases in DuckDB to prevent the system from re-reading the tables from MySQL continuously, particularly for large tables.

Data can be copied over from MySQL to DuckDB using standard SQL, for example:

CREATE TABLE duckdb_table AS FROM mysqlscanner.mysql_table;

Writing Data to MySQL

In addition to reading data from MySQL, create tables, ingest data into MySQL and make other modifications to a MySQL database using standard SQL queries.

This allows you to use DuckDB to, for example, export data that is stored in a MySQL database to Parquet, or read data from a Parquet file into MySQL.

Below is a brief example of how to create a new table in MySQL and load data into it.

ATTACH 'host=localhost user=root port=0 database=mysqlscanner' AS mysql_db (TYPE mysql_scanner);
CREATE TABLE mysql_db.tbl (id INTEGER, name VARCHAR);
INSERT INTO mysql_db.tbl VALUES (42, 'DuckDB');

Many operations on MySQL tables are supported. All these operations directly modify the MySQL database, and the result of subsequent operations can then be read using MySQL. Note that if modifications are not desired, ATTACH can be run with the READ_ONLY property which prevents making modifications to the underlying database. For example:

ATTACH 'host=localhost user=root port=0 database=mysqlscanner' AS mysql_db (TYPE mysql_scanner, READ_ONLY);

Supported Operations

Below is a list of supported operations.

CREATE TABLE

CREATE TABLE mysql_db.tbl (id INTEGER, name VARCHAR);

INSERT INTO

INSERT INTO mysql_db.tbl VALUES (42, 'DuckDB');

SELECT

SELECT * FROM mysql_db.tbl;
┌───────┬─────────┐
│  id   │  name   │
│ int64 │ varchar │
├───────┼─────────┤
│    42 │ DuckDB  │
└───────┴─────────┘

COPY

COPY mysql_db.tbl TO 'data.parquet';
COPY mysql_db.tbl FROM 'data.parquet';

UPDATE

UPDATE mysql_db.tbl
SET name = 'Woohoo'
WHERE id = 42;

DELETE

DELETE FROM mysql_db.tbl
WHERE id = 42;

ALTER TABLE

ALTER TABLE mysql_db.tbl
ADD COLUMN k INTEGER;

DROP TABLE

DROP TABLE mysql_db.tbl;

CREATE VIEW

CREATE VIEW mysql_db.v1 AS SELECT 42;

CREATE SCHEMA and DROP SCHEMA

CREATE SCHEMA mysql_db.s1;
CREATE TABLE mysql_db.s1.integers (i INT);
INSERT INTO mysql_db.s1.integers VALUES (42);
SELECT * FROM mysql_db.s1.integers;
┌───────┐
│   i   │
│ int32 │
├───────┤
│    42 │
└───────┘
DROP SCHEMA mysql_db.s1;

Transactions

CREATE TABLE mysql_db.tmp (i INTEGER);
BEGIN;
INSERT INTO mysql_db.tmp VALUES (42);
SELECT * FROM mysql_db.tmp;
┌───────┐
│   i   │
│ int64 │
├───────┤
│    42 │
└───────┘
ROLLBACK;
SELECT * FROM mysql_db.tmp;
┌────────┐
│   i    │
│ int64  │
├────────┤
│ 0 rows │
└────────┘

The DDL statements are not transactional in MySQL.

Settings

Name Description Default
mysql_bit1_as_boolean Whether or not to convert BIT(1) columns to BOOLEAN true
mysql_debug_show_queries DEBUG SETTING: print all queries sent to MySQL to stdout false
mysql_experimental_filter_pushdown Whether or not to use filter pushdown (currently experimental) false
mysql_tinyint1_as_boolean Whether or not to convert TINYINT(1) columns to BOOLEAN true

Schema Cache

To avoid having to continuously fetch schema data from MySQL, DuckDB keeps schema information - such as the names of tables, their columns, etc - cached. If changes are made to the schema through a different connection to the MySQL instance, such as new columns being added to a table, the cached schema information might be outdated. In this case, the function mysql_clear_cache can be executed to clear the internal caches.

CALL mysql_clear_cache();