Connect to Redis as an External Data Source using PolyBase

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Redis ODBC Driver

The Redis ODBC Driver is a powerful tool that allows you to connect with Redis high-performance data stores, directly from any applications that support ODBC connectivity.

Read, write, and update Redis data through a standard ODBC Driver interface.



Use the CData ODBC Driver for Redis and PolyBase to create an external data source in SQL Server 2019 with access to live Redis data.

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 Redis, you get access to your Redis data directly alongside your SQL Server data. This article walks through creating an external data source and external tables to grant access to live Redis data using T-SQL queries.

The CData ODBC drivers offer unmatched performance for interacting with live Redis data using PolyBase due to optimized data processing built into the driver. When you issue complex SQL queries from SQL Server to Redis, the driver pushes down supported SQL operations, like filters and aggregations, directly to Redis and utilizes the embedded SQL engine to process unsupported operations (often SQL functions and JOIN operations) client-side. And with PolyBase, you can also join SQL Server data with Redis data, using a single query to pull data from distributed sources.

Connect to Redis

If you have not already, first specify connection properties in an ODBC DSN (data source name). This is the last step of the driver installation. You can use the Microsoft ODBC Data Source Administrator to create and configure ODBC DSNs. To create an external data source in SQL Server using PolyBase, configure a System DSN (CData Redis Sys is created automatically).

Set the following connection properties to connect to a Redis instance:

  • Server: Set this to the name or address of the server your Redis instance is running on. You can specify the port in Port.
  • Password: Set this to the password used to authenticate with a password-protected Redis instance , using the Redis AUTH command.

Set UseSSL to negotiate SSL/TLS encryption when you connect.

Click "Test Connection" to ensure that the DSN is connected to Redis properly. Navigate to the Tables tab to review the table definitions for Redis.

Create an External Data Source for Redis Data

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

Creating a Master Encryption Key

Execute the following SQL command to create a new master key, 'ENCRYPTION,' to encrypt the credentials for the external data source.

CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'password';

Creating a Credential Database

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

NOTE: Since Redis does not require a User or Password to authenticate, you may use whatever values you wish for IDENTITY and SECRET.

CREATE DATABASE SCOPED CREDENTIAL redis_creds
WITH IDENTITY = 'username', SECRET = 'password';

Create an External Data Source for Redis

Execute the following SQL command to create an external data source for Redis with PolyBase, using the DSN and credentials configured earlier.

NOTE: SERVERNAME and PORT corresponds to the Server and Port connection properties for Redis. PUSHDOWN is set to ON by default, meaning the ODBC Driver can leverage server-side processing for complex queries.

CREATE EXTERNAL DATA SOURCE cdata_redis_source
WITH ( 
  LOCATION = 'odbc://SERVERNAME[:PORT]',
  CONNECTION_OPTIONS = 'DSN=CData Redis Sys',
  -- PUSHDOWN = ON | OFF,
  CREDENTIAL = redis_creds
);

Create External Tables for Redis

After creating the external data source, use CREATE EXTERNAL TABLE statements to link to Redis data from your SQL Server instance. The table column definitions must match those exposed by the CData ODBC Driver for Redis. You can refer to the Tables tab of the DSN Configuration Wizard to see the table definition.

Sample CREATE TABLE Statement

The statement to create an external table based on a Redis Customers would look similar to the following:

CREATE EXTERNAL TABLE Customers(
  City [nvarchar](255) NULL,
  CompanyName [nvarchar](255) NULL,
  ...
) WITH ( 
  LOCATION='Customers',
  DATA_SOURCE=cdata_redis_source
);

Having created external tables for Redis in your SQL Server instance, you are now able to query local and remote data simultaneously. Thanks to built-in query processing in the CData ODBC Driver, you know that as much query processing as possible is being pushed to Redis, freeing up local resources and computing power. Download a free, 30-day trial of the ODBC Driver for Redis and start working with live Redis data alongside your SQL Server data today.