Connect to MySQL Data as an External Data Source using PolyBase

PolyBase for SQL Server allows you to query external data by using the same Transact-SQL syntax used to query a database table. When paired with the CData ODBC Driver for MySQL, you get access to your MySQL data directly alongside your SQL Server data. This article describes creating an external data source and external tables to grant access to live MySQL data using T-SQL queries.

NOTE: PolyBase is only available on SQL Server 19 and above.

CData Connect AI provides a pure SQL Server interface for MySQL, allowing you to query data from MySQL without replicating the data to a natively supported database. Using optimized data processing out of the box, CData Connect AI pushes all supported SQL operations (filters, JOINs, etc.) directly to MySQL, leveraging server-side processing to return the requested MySQL data quickly.

Configure MySQL Connectivity for PolyBase

Connectivity to MySQL from PolyBase is made possible through CData Connect AI. To work with MySQL data from PolyBase, we start by creating and configuring a MySQL connection.

1. Log into Connect AI, click Sources, and then click Add Connection
👁 Adding a Connection

2. Select "MySQL" from the Add Connection panel
👁 Selecting a data source

3. Enter the necessary authentication properties to connect to MySQL.

   The CData Provider supports connecting to on-premises and cloud-hosted versions of MySQL such as Amazon RDS for MySQL, Google Cloud SQL for MySQL, Azure Database for MySQL, or Oracle MySQL HeatWave. The Server and Port properties must be set to a MySQL server. If IntegratedSecurity is set to false, then User and Password must be set to valid user credentials. Optionally, Database can be set to connect to a specific database. If not set, tables from all databases will be returned.

   SSH Connectivity for MySQL

   You can use SSH (Secure Shell) to authenticate with MySQL, whether the instance is hosted on-premises or in supported cloud environments. SSH authentication ensures that access is encrypted (as compared to direct network connections).

   SSH Connections to MySQL in Password Auth Mode

   To connect to MySQL via SSH in Password Auth mode, set the following connection properties:

   • User: MySQL User name
   • Password: MySQL Password
   • Database: MySQL database name
   • Server: MySQL Server name
   • Port: MySQL port number like 3306
   • UserSSH: "true"
   • SSHAuthMode: "Password"
   • SSHPort: SSH Port number
   • SSHServer: SSH Server name
   • SSHUser: SSH User name
   • SSHPassword: SSH Password

   SSH Connections to MySQL in Public Key Auth Mode

   To connect to MySQL via SSH in Password Auth mode, set the following connection properties:

   • User: MySQL User name
   • Password: MySQL Password
   • Database: MySQL database name
   • Server: MySQL Server name
   • Port: MySQL port number like 3306
   • UserSSH: "true"
   • SSHAuthMode: "Public_Key"
   • SSHPort: SSH Port number
   • SSHServer: SSH Server name
   • SSHUser: SSH User name
   • SSHClientCret: the path for the public key certificate file
   👁 Configuring a connection (Salesforce is shown)
   
4. Click Save & Test
5. Navigate to the Permissions tab in the Add MySQL Connection page and update the User-based permissions. 👁 Updating permissions
   

Add a Personal Access Token

When connecting to Connect AI through the REST API, the OData API, or the Virtual SQL Server, a Personal Access Token (PAT) is used to authenticate the connection to Connect AI. It is best practice to create a separate PAT for each service to maintain granularity of access.

1. Click on the Gear icon () at the top right of the Connect AI app to open the settings page.
2. On the Settings page, go to the Access Tokens section and click Create PAT.
3. Give the PAT a name and click Create. 👁 Creating a new PAT
   
4. The personal access token is only visible at creation, so be sure to copy it and store it securely for future use.

With the connection configured and a PAT generated, you are ready to connect to MySQL data from Polybase.

Create an External Data Source for MySQL Data

After configuring the connection, you need to create a credential database for the external data source.

Creating a Credential Database

Execute the following SQL command to create credentials for the external data source connected to MySQL data.

NOTE: Set IDENTITY to your Connect AI username and set SECRET to your Personal Access Token.

CREATE DATABASE SCOPED CREDENTIAL ConnectCloudCredentials
WITH IDENTITY = 'yourusername', SECRET = 'yourPAT';

Create an External Data Source for MySQL

Execute a CREATE EXTERNAL DATA SOURCE SQL command to create an external data source for MySQL with PolyBase:

CREATE EXTERNAL DATA SOURCE ConnectCloudInstance
WITH ( 
 LOCATION = 'sqlserver://tds.cdata.com:14333',
 PUSHDOWN = ON,
 CREDENTIAL = ConnectCloudCredentials
);

Create External Tables for MySQL

After creating the external data source, use CREATE EXTERNAL TABLE statements to link to MySQL data from your SQL Server instance. The table column definitions must match those exposed by CData Connect AI. You can use the Data Explorer in Connect AI to see the table definition.

👁 Table definition in the Data Explorer (Salesforce is shown)

Sample CREATE TABLE Statement

Execute a CREATE EXTERNAL TABLE SQL command to create the external table(s), using the collation and setting the LOCATION to three-part notation for the connection, catalog, and table. The statement to create an external table based on a MySQL Orders would look similar to the following.

CREATE EXTERNAL TABLE Orders(
 ShipName COLLATE [nvarchar](255) NULL,
 Freight COLLATE [nvarchar](255) NULL,
 ...
) WITH ( 
 LOCATION='MySQL1.MySQL.Orders',
 DATA_SOURCE=ConnectCloudInstance
);

Having created external tables for MySQL in your SQL Server instance, you are now able to query local and remote data simultaneously. To get live data access to hundreds of SaaS, Big Data, and NoSQL sources directly from your SQL Server database, try CData Connect AI today!