MySQL Connector

The MySQL connector allows querying and creating tables in an external MySQL database. This can be used to join data between different systems like MySQL and Hive, or between two different MySQL instances.

Configuration

To configure the MySQL connector, create a catalog properties file in etc/catalog named, for example, mysql.properties, to mount the MySQL connector as the mysql catalog. Create the file with the following contents, replacing the connection properties as appropriate for your setup:

connector.name=mysql
connection-url=jdbc:mysql://example.net:3306
connection-user=root
connection-password=secret

The connection-url defines the connection information and parameters to pass to the MySQL JDBC driver. The supported parameters for the URL are available in the MySQL Developer Guide.

For example, the following connection-url allows you to configure the JDBC driver to interpret time values based on UTC as a timezone on the server, and serves as a workaround for a known issue.

connection-url=jdbc:mysql://example.net:3306?serverTimezone=UTC

The connection-user and connection-password are typically required and determine the user credentials for the connection, often a service user.

Multiple MySQL Servers

You can have as many catalogs as you need, so if you have additional MySQL servers, simply add another properties file to etc/catalog with a different name (making sure it ends in .properties). For example, if you name the property file sales.properties, Presto will create a catalog named sales using the configured connector.

General Configuration Properties

Querying MySQL

The MySQL connector provides a schema for every MySQL database. You can see the available MySQL databases by running SHOW SCHEMAS:

SHOW SCHEMAS FROM mysql;

If you have a MySQL database named web, you can view the tables in this database by running SHOW TABLES:

SHOW TABLES FROM mysql.web;

You can see a list of the columns in the clicks table in the web database using either of the following:

DESCRIBE mysql.web.clicks;
SHOW COLUMNS FROM mysql.web.clicks;

Finally, you can access the clicks table in the web database:

SELECT * FROM mysql.web.clicks;

If you used a different name for your catalog properties file, use that catalog name instead of mysql in the above examples.

Type mapping

PrestoDB and MySQL each support types that the other does not. When reading from or writing to MySQL, Presto converts the data types from MySQL to equivalent Presto data types, and from Presto to equivalent MySQL data types. Refer to the following sections for type mapping in each direction.

MySQL to PrestoDB type mapping

The connector maps MySQL types to the corresponding PrestoDB types:

No other types are supported.

PrestoDB to MySQL type mapping

The connector maps PrestoDB types to the corresponding MySQL types:

No other types are supported.

SQL Support

The MySQL connector allows querying and creating MySQL tables. Here are some examples of the SQL operations supported:

ALTER TABLE

ALTER TABLE mysql.web.page_views ADD COLUMN zipcode VARCHAR;
ALTER TABLE mysql.web.page_views RENAME COLUMN zipcode TO location;
ALTER TABLE mysql.web.page_views DROP COLUMN location;

CREATE TABLE

Create a new MySQL table named page_views in the web schema:

CREATE TABLE mysql.web.page_views (
  user_id bigint,
  page_url varchar,
  ds date,
  country varchar
);

Note

Presto does not enforce primary key constraints. For example, the following statement

CREATE TABLE users (
        id INT PRIMARY KEY,
        name TEXT,
        email TEXT
    );

returns an error similar to the following:

Query 20240322_095447_00010_syzb3 failed: line 2:19: mismatched input 'PRIMARY'. Expecting: ')', ','

CREATE TABLE AS SELECT

Create a new table page_views_new from an existing table page_views:

CREATE TABLE mysql.web.page_views_new AS SELECT * FROM mysql.web.page_views;

Note

Advanced SQL features such as data compression are not supported in the CREATE TABLE AS SELECT statement.

CREATE TABLE compressed_employees AS SELECT * FROM employees WITH (compression = 'Zlib');

returns an error similar to the following:

Query 20240321_103408_00015_kbd43 failed: line 1:67: mismatched input '('. Expecting: 'DATA', 'NO'

INSERT INTO

Insert data into the page_views table:

INSERT INTO mysql.web.page_views VALUES(1, 'https://example.com', current_date, 'country');

SELECT

SELECT * FROM mysql.web.page_views;

TRUNCATE

Delete all of the data from the table page_views without dropping the table:

TRUNCATE TABLE mysql.web.page_views;

MySQL Connector Limitations

The following SQL statements are not supported:

• ALTER TABLE

• ANALYZE

• CREATE SCHEMA

• CREATE VIEW

• DELETE

• DROP SCHEMA

• DROP TABLE

• DROP VIEW

• GRANT

• REVOKE

• SHOW GRANTS

• SHOW ROLE GRANTS

• SHOW ROLES

• UPDATE